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microscope

microscope

microscope Sentence Examples

  • In polarized light they show a weak grey colour with a black cross, the arms of which are parallel to the cobwebs in the eyepiece of the microscope and remain stationary when the section is rotated.

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  • The plant can then be at any time examined under the microscope without injuring the mounted specimen.

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  • Under the microscope the ovary is seen to be covered by a FIG.

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  • The microscopes adjoining 82 read the position and declination circles; for, by an ingenious arrangement of prisms and screens, the images of both circles can be read by each single microscope as shown in fig.

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  • The microscopes adjoining 82 read the position and declination circles; for, by an ingenious arrangement of prisms and screens, the images of both circles can be read by each single microscope as shown in fig.

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  • It consists of a definite contractile sac or sacs lying on the dorsal side of the alimentary canal near the oesophagus, and in preparations of Terebratulina made by quickly removing the viscera and examining them in sea-water under a microscope, he was able to count the pulsations, which followed one another at intervals of 30-40 seconds.

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  • a is the eye-piece, b the handle for moving the segments, c the micrometer microscope for reading the scales and scale micrometer, d the micrometer readers of the position and declination circles, e the handle for rotating the large wheel E which carries the screens.

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  • As rotifers are common in ponds, the first workers with the microscope observed them repeatedly, the first record being that of John Harris in 1696, who found a Bdelloid in a gallipot that had been standing in his window.

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  • So in the microscope there is nothing except lack of light to hinder the visibility of an object however small.

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  • 4, AB represents the axis of an optical instrument (telescope or microscope), A being a point of the object and B a point of the image.

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  • In 1665, physicist Robert Hooke pointed a microscope at a piece of cork and noticed many small compartments he called "cells."

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  • A special microscope is introduced for determining the division errors of the scales.

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  • Instead of a mirror the second fork carries a bright point on one prong, and the microscope is focused on this.

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  • The microscope shows that the neighbouring filaments are held together by patches of cilia, called " ciliated junctions," which interlock with one another just as two brushes may be made to do.

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  • The microscope or viewing telescope is fitted with a spider-line micrometer having two screws at right angles to each other, by means of which readings can be made first on one reseau-line, then on the star, and finally on the opposite reseau-line in both co-ordinates.

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  • If both forks vibrate, an observer looking through the microscope sees the bright point describing Lissajous figures.

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  • In fact the uniformity of brass and bell-metal is only superficial; if we adopt the methods described in the article Metallography, and if, after polishing a plane face on a bit of gun-metal, we etch away the surface layer and examine the new surface with a lens or a microscope, we find a complex pattern of at least two materials.

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  • He also made great use of the simple dark chamber for his optical experiments with prisms, &c. Joseph Priestley (1772) mentions the application of the solar microscope, both to the small and portable and the large camera obscura.

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  • means of measuring the focal point were provided; symmetrical motion was given to the slides; scales on each slide were provided instead of screws for measuring the separation of the segments, and both scales were read by the same micrometer microscope; a metallic thermometer was added to determine the temperature of the scales.

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  • It is, like milk, an emulsion, and when examined with the microscope is seen to consist of numerous globules suspended in a watery fluid.

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  • The application, unaccountably long delayed, of this principle to the microscope by H.

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  • Quekett in his Treatise on the Microscope ascribes to Ramsden the practical introduction of the spider web in micrometers.

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  • The statement of the law of resolving power has been made in a form appropriate to the microscope, but it admits also of immediate application to the telescope.

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  • 37), in which it is possible most satisfactorily to study in the living animal, by means of the microscope, the course of the blood-stream, and also the reno-pericardial communication.

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  • Often this felsitic devitrified glass is so fine-grained that its constituents cannot be directly determined even with the aid of the microscope, but chemical analysis leaves little doubt as to the real nature cf the minerals which have been formed.

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  • The energy of this fork with a given amplitude of vibration could be calculated from its dimensions and elasticity, and the amplitude was observed by measuring with a microscope the line into which the image of a starch grain on the prong was drawn by the vibration.

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  • A comparison with the method of a material pointer, attached to the parts whose rotation is under observation, and viewed through a microscope, is of interest.

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  • a microscope cover-glass, held close to the eye and inclined at an angle of 45° to the horizon, one can See the images of objects in front, formed by reflection from the surface of the glass, and at the same time one can also see through the transparent glass.

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  • Lockhart Clarke (1817-1880), one of the earliest investigators of nervous pathology, the improvement of the compound microscope had not attained the achromatism, the penetration and the magnification which have since enabled J.

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  • It takes a comprehensive view of all the plants which cover the earth, from the minutest organism, only visible by the aid of the microscope, to the most gigantic productions of the tropics.

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  • It takes a comprehensive view of all the plants which cover the earth, from the minutest organism, only visible by the aid of the microscope, to the most gigantic productions of the tropics.

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  • At a later period he was one of the leading contributors to the Encyclopaedia Britannica (seventh and eighth editions), the articles on Electricity, Hydrodynamics, Magnetism, Microscope, Optics, Stereoscope, Voltaic Electricity, &c., being from his pen.

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  • It was not until the 19th century that the microscope, thus early applied by Leeuwenhoek, Malpighi, Hook and Swammerdam to the study of animal structure, was perfected as an instrument, and accomplished for zoology its final and most important service.

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  • Instead of a mirror, the objective of a microscope is attached to one prong of the first fork and the eyepiece of the microscope is fixed behind the fork.

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  • Instead of a mirror, the objective of a microscope is attached to one prong of the first fork and the eyepiece of the microscope is fixed behind the fork.

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  • When the sieve-tube has ceased to function and the protoplasm, slime strings, and callose have disappeared, the perforations through which the slime strings passed are left as relatively large holes, easily visible in some cases with low powers of the microscope, piercing the sieve.plate.

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  • (d) The scales are made of iridio-platinum instead of silver, and the magnifying power of the reading microscope is increased fourfold (viz.

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  • In this way the scale can be viewed by a microscope of much higher magnifying power than can be employed for the photographed spectrum.

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  • The development of the compound microscope rendered possible the accurate study of their life-histories; and the publication in 1851 of the results of Wilhelm Hofmeister's researches on the comparative embryology of the higher Cryptogamia shed a flood of light on their relationships to each other and to the higher plants, and supplied the basis for the distinction of the great groups Thallophyta, Bryophyta, Pteridophyta and Phanerogamae, the last named including Gymnospermae and Angiospermae.

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  • Hales (1727I 733) discussed the rotting of wounds, cankers, &c., but much had to be done with the microscope before any real progress was possible, and it is easily intelligible that until the theory of nutrition of the higher plants had been founded by the work of Ingenhouss, Priestley and De Saussure, the way was not even prepared for accurate knowledge of cryptogamic parasites and the diseases they induce.

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  • Hales (1727I 733) discussed the rotting of wounds, cankers, &c., but much had to be done with the microscope before any real progress was possible, and it is easily intelligible that until the theory of nutrition of the higher plants had been founded by the work of Ingenhouss, Priestley and De Saussure, the way was not even prepared for accurate knowledge of cryptogamic parasites and the diseases they induce.

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  • The limiting efficiency of the microscope is attained when the angular aperture amounts to 180°; and it is evident that a lateral displacement of the point under observation through -IX entails (at the old image) a phase-discrepancy B Q' of a whole period, one extreme ray FIG.

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  • In the mutual behaviour of such cells, toxins, and antitoxins, and again of microbes themselves, we may demonstrate even on the field of the microscope some of the modes of such actions, which seem to partake in great measure at any rate of a chemical quality (agglutinins, coagulins, chemotaxis).

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  • On the 6th of November in that year he plainly saw the living parasites under the microscope in the blood of a malarial patient, and he shortly afterwards communicated his observations to the Paris Academie de Medecine.

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  • The term Cryptogam is archaic, implying a hidden method of reproduction as compared with the obvious method represented by the flower of the Phanerogam; with the aid of a good microscope it is, however, easier to follow the process of fertilization.

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  • The image of a normal reseau-square, as viewed in the microscope, shall exactly coincide with the square formed by the fixed webs - that is to say, the image of the sides of a normal reseau-square shall measure exactly io screw-revolutions.

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  • The remedy proposed by Repsold for this proved fault is to cause the whole slide to tilt instead of the microscope only; this should prove a complete remedy.

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  • If 2R be the diameter of the objectglass and D the distance of the object, the angle subtended by AP is E/D, and the angular resolving power is given by X/2 D sin a = X/2 R (3) This method of derivation (substantially due to Helmholtz) makes it obvious that there is no essential difference of principle between the two cases, although the results are conveniently stated in different forms. In the case of the telescope we have to deal with a linear measure of aperture and an angular limit of resolution, whereas in the case of the microscope the limit of resolution is linear, and it is expressed in terms of angular aperture.

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  • The excellent manner in which the scales and micrometers are mounted, the employment of a compound microscope for viewing the scales, with its ingeniously arranged and admirably efficient reversing prism, and the perfection of its slow motions for focusing and reading, combine to render this a most accurate and convenient instrument for very refined measures, although too slow for work in which the measures must depend on single pointings in each of two reversed positions of the plate, and where speed of working is essential.

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  • This form of the instrument is often used in conjunction with the microscope, the mirror being attached to the eye-piece and the tube of the microscope being placed horizontally.

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  • This form of the instrument is often used in conjunction with the microscope, the mirror being attached to the eye-piece and the tube of the microscope being placed horizontally.

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  • In some cases it shows, when submitted to a careful examination under the highest powers of the microscope, and especially when treated with reagents of various kinds, traces of a more or less definite structure in the form of a meshwork consisting of a clear homogeneous substance containing numerous minute bodies known as microsomes, the spaces being filled by a more fluid ground-substance.

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  • The capillary tube can be raised or lowered at will by running a magnet outside the tube, and the heights of the columns are measured by a cathetometer or micrometer microscope.

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  • Stoney, the restriction is often, perhaps usually, violated in the microscope.

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  • It is, however, not possible to detect the copper in the silver by means of the microscope.

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  • The chilling stereotypes the structure existing in the ingot at the moment it was withdrawn from the furnace, and we can af terwards study this structure by means of the microscope.

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  • The word is also used as a unit of linear measurement of the magnifying power of a lens or microscope.

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  • In the verification of weights and measures a margin of error is permitted to manufacturers and scale-makers, as it is found to be impossible to make two weights, or two measures, so identical that between them some difference may not be found either by the balance or the microscope.

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  • His name is best known for the improvements he effected in the mirrors of reflecting telescopes and especially in the construction of the microscope.

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  • The rod-like appearance of silk and its absence of markings under the microscope are also easily recognizable features of the fibre.

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  • On cutting across a grain of rice and examining it under the microscope, first the flattened and dried cells of the husk are seen, and then one or two layers of cells elongated in a direction parallel to the length of the seed, which contain the gluten or nitrogenous matter.

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  • Sorby and, later, Abbe, designed instruments on the same principle to be used in connexion with the microscope.

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  • The needle b is then substituted for a, there being now no needle in the clamp attached to the microscope arm, and the difference between the reading now obtained and the dip, together with the weight added to the needle, gives the product of the moment of the needle b into the earth's total force.

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  • In some solutions they are visible under a good microscope.

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  • Among those directly visible to the microscope are oil drops, often coloured (Uredineae) crystals of calcium oxalate (Phallus, Russula), proteid crystals (Mucor, Pilobolus, &c.) and resin (Polyporei).

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  • Invisible to the microscope, but rendered visible by reagents, are glycogen, Mucor, Ascomycetes, yeast, &c. In addition to these cell-contents we have good indirect evidence of the existence of large series of other bodies, such as proteids, carbohydrates, organic acids, alkaloids, enzymes, &c. These must not be confounded with the numerous substances obtained by chemical analysis of masses of the fungus, as there is often no proof of the manner of occurrence of such bodies, though we may conclude with a good show of probability that some of them also exist preformed in the living cell.

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  • About fifty species of Saccharomyces are described more or less completely, but since many of these cannot be distinguished by the microscope, and some have been found to develop physiological races or varieties under special conditions of - ?u growth, the limits are still far too ill-defined for complete ep botanical treatment of the genus.

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  • Constitution of Iron and Steel.-The constitution of the various classes of iron and steel as shown by the microscope explains readily the great influence of carbon which was outlined in §§ 2 and 3.

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  • Some species are minute filamentous plants, requiring the microscope for their detection; others, like Lessonia, are of considerable bulk, or, like Macrocystis, of enormous length.

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  • In point of size the largest cannot rival the larger Brown Algae, while the majority require the aid of the microscope for their investigation.

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  • These passages certainly prove that Bacon had very nearly, if not perfectly, arrived at theoretical proof of the possibility of constructing a telescope and a microscope; but his writings give no account of the trial of an actual telescope, nor any detailed results of the application of a telescope to an examination of the heavens.

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  • If we now attach to the polar axis a graduated circle D D, called the" hour circle,"of which the microscope or vernier R reads o h when the declination axis is horizontal, we can obviously read off the hour angle from the meridian of any star to which the telescope may be directed at the instant of observation.

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  • This investigation is also memorable because he detected the minute sugar-crystals in the roots by the help of the microscope, which was thus introduced as an adjunct to chemical inquiry.

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  • Any divergence or collapse of the gold-leaf can be viewed by a microscope through an aperture in the side of the case.

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  • If then the strip of gold-leaf is raised or lowered in potential it moves to or from the plate P, and its movement can be observed by a microscope through a hole in the side of the box.

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  • divisions of the micrometer scale in the eye-piece of the microscope, 54 divisions being equal to one millimetre.

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  • Several green-coloured beetles are, on account of their colour, used as adulterants to cantharides, but they are very easily detected by examination with the eye, or, if powdered, with the microscope.

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  • The micro-organism giving rise to this disease generally appears in the form of small jointed rods and tangled masses under the microscope.

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  • The following may be regarded as typical: - (t) Largest aperture; necessary corrections are - for the axis point, and sine condition; errors of the field of view are almost disregarded; example - highpower microscope objectives.

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  • Abbe succeeded in computing microscope objectives free from error of the axis point and satisfying the sine condition for several colours, which therefore, according to his definition, were " aplanatic for several colours "; such systems he termed " apochromatic."

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  • This Is Produced In The Same Amount, But In The Opposite Sense, By The Oculars, Which Are Used With These Objectives (" Compensating Oculars "), So That It Is Eliminated In The Image Of The Whole Microscope.

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  • The Best Telescope Objectives, And Photographic Objectives Intended For Three Colour Work, Are Also Apochromatic, Even If They Do Not Possess Quite The Same Quality Of Correction As Microscope Objectives Do.

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  • The fungus is very small in size, and under the microscope appears slightly whitish or colourless.

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  • Until about 1725 the belief was very prevalent that cochineal was the seed of a plant, but Dr Martin Lister in 1672 conjectured it to be a kind of kermes, and in 1703 Antony van Leeuwenhoek ascertained its true nature by aid of the microscope.

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  • The presence in the root of starch, resin and oxalate of lime is revealed by the use of the microscope.

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  • THE Study Of Bacteria The general advances which have been made of late years in the study of bacteria are clearly brought to mind when we reflect that in the middle of the 19th century these organisms were only known to a few experts and in a few forms as curiosities of the microscope, chiefly interesting for their minuteness and motility.

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  • nutri' nt gelatine is fixed under the microscope and kept at constant temperature, a curve of growth can be obtained recording the behaviour during many hours or days.

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  • The microscope magnifies the distance traversed as well as the organism, and although a bacterium which covers 9 - ro cm.

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  • (i) the discovery of a bacterium in the affected tissues by means of the microscope; (2) the obtaining of the bacterium in pure culture; and (3) the production of the disease by inoculation with a pure culture.

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  • The process is of course observed by means of the microscope, but the clumps soon settle in the fluid and ultimately form a sediment, leaving the upper part clear.

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  • The discovery of the microscope carried the refutation further.

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  • In "frilling" or "frilled structure" the folds have still smaller amplitude, and in many highly corrugated rocks minute folds are observable with the microscope that do not appear to the unaided eye.

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  • The ovary adheres firmly to the seed in the interior, so that on examining a longitudinal section of the grain by the microscope the outer layer is seen to consist of epidermal cells, of which the uppermost are prolonged into short hairs to cover the apex of the grain.

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  • He greatly improved both the telescope and microscope.

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  • The invention of the microscope, attributed to Galileo by his first biographer, Vincenzio Viviani, does not in truth belong to him.

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  • Such an instrument was made as early as 1590 by Zacharias Jansen of Middleburg; and although Galileo discovered, in 1610, a means of adapting his telescope to the examination of minute objects, he did not become acquainted with the compound microscope until 1624 when he saw one of Drebbel's instruments in Rome, and, with characteristic ingenuity, immediately introduced some material improvements into its construction.

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  • C. Stokes, The Microscope (Detroit, 1887-1888); C. Zelinka, Zeitschr.

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  • MICROSCOPE (Gr.

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  • A simple microscope consists of a single positive lens, or of a lens combination acting as a single lens, placed between the eye and the object so that it presents a virtual and enlarged image.

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  • The compound microscope generally consists of two positive lens systems, so arranged that the system nearer the object (termed the objective) projects a real enlarged image, which occupies the same place relatively to the second system (the eyepiece or ocular) as does the real object in the simple microscope.

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  • Convex glass lenses were first generally used to assist ordinary vision as " spectacles "; and not only were spectacle-makers the first to produce glass magnifiers (or simple microscopes), but by them also the telescope and the compound microscope were first invented.

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  • During the Thirty Years' War the simple microscope was widely known.

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  • Antony van Leeuwenhoek appears to be the first to succeed in grinding and polishing lenses of such short focus and perfect figure as to render the simple microscope a better instrument for most purposes than any compound microscope then constructed.

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  • At that time the " compass " microscope was in use.

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  • Early opticians and microscopists gave their chief attention to the improvement of the simple microscope, the principle of which we now explain.

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  • Simple Microscope Position and Size of the Image.

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  • When the details are no longer recognizable by the unaided eye, the magnifying glass or the simple microscope is necessary.

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  • As a rule large magnification is not demanded from the former, but a larger field of view, whilst the simple microscope should ensure powerful magnification even when the field is small.

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  • The simple microscope enlarges the angle of vision, and does not tire the eye when it is arranged so that the image lies in the farthest limit of distinct vision (the punctum remotum).

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  • Since H' P = F 0, = y, from the focal length of the simple microscope, the visual angle w' is given by tan w'/y=I/f'=V, (I) in which f', = H' F', is the image-side focal length (see Lens).

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  • In most cases the number of " diameters " of the simple microscope is required; i.e.

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  • the ratio between the apparent sizes of the object when observed through the microscope and when viewed by the naked eye.

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  • Since this value for the distance of distinct vision is only conventional, it is understood that the capacity of the simple microscope given in (2) holds good only for eyes accustomed to examine small objects io in.

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  • The magnification, resulting from the simple microscope of i in.

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  • From this it appears that each observer obtains specific advantages from one and the same simple microscope, and also the individual observer can obtain different magnifications by either using different accommodations, or by viewing in passive accommodation.

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  • The simple microscope permits such vision.

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  • Triplets are employed when the focal length of the simple microscope was less than in.

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  • To an achromatic collective lens, which is turned towards the object, a dispersive lens is combined (this type to a certain extent belongs to the compound microscope).

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  • Compound Microscope The view held by early opticians, that a compound microscope could never produce such good images as an instrument of the simple type, has proved erroneous; and the principal attention of modern opticians has been directed to the compound instrument.

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  • Although we now know how the errors of lenses may be corrected, and how the simple microscope may be improved, this instrument remains with relatively feeble magnification, and to obtain stronger magnifications the compound form is necessary.

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  • A microscope objective being made in essentially the same way as a simple microscope, and the front focus of the compound system being situated before the front focus of the objective, the magnification due to the simple system makes the free object distance greater than that obtained with a simple microscope of equal magnification.

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  • Moreover, this distance between the object and eye is substantially increased in the compound microscope by the stand; the inconveniences, and in certain circumstances also the dangers, to the eye which may arise, for example by warming the object, are also avoided.

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  • This permits researches which are impossible with the simple microscope.

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  • For example, the real image may be recorded on a photographic plate; it may be measured; it can be physically altered by polarization, by spectrum analysis of the light employed by absorbing layers, &c. The greatest advantage of the compound microscope is that it represents a larger area, and this much more completely than is possible in the simple form.

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  • The simple microscope is subject to either limitation.

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  • As we shall see later, one of the principal functions of the microscope objective is the representation with wide pencils.

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  • In that case, however, in the compound microscope a small object may always be represented by means of wider pencils, one of the foci of the objective (not of the collective system) being near it.

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  • In 1646 Fontana described a microscope which had a positive eyepiece.

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  • The development of the compound microscope essentially depends on the improvement of the objective; but no distinct improvement was made in its construction in the two centuries following the discovery.

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  • A microscope, using concave mirrors, was proposed in 1672 by Sir Isaac Newton; and he was succeeded by Barker, R.

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  • thick, called the cover-slip. If we consider the production of the image of an object of this kind by the two positive systems of a compound microscope shown in fig.

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  • Weak and strong microscope objectives act differently.

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  • When forming an image by a microscope objective it often happens that the transparent media bounding the system have different optical properties.

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  • The image viewed through the eyepiece appears then to the observer under the angle w", and as with the single microscope tan w" = I /f 2 ' (4) where f' 2 is the image-side focal length of the eyepiece.

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  • - Ray transmission in compound microscope with a positive ocular.

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  • P"P 1 " = exit pupil of complete microscope.

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  • To obtain the magnification of the complete microscope we must combine the objective magnification M with the action of the eyepiece.

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  • If we replace y' in equation (4) by the value given by (3), we obtain tan w"/ y i/f2"=V, (5) the magnification of the complete microscope.

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  • The magnification is also expressed as the ratio of the apparent size of the object observed through the microscope to the apparent size of the object seen with the naked eye.

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  • If this value of y be inserted in equation (5), we obtain the magnification number of the compound microscope N =tan w"/ tan w =Ol/f i 'f 2 ' =Vl.

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  • As with the simple microscope, different observers see differently in the same compound microscope; and hence the magnification varies with the power of accommodation.

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  • The image produced by a microscope formed of two positive systems (fig.

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  • The simplest microscope which produces an upright image has a negative lens as eyepiece.

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  • P "P1' =virtual image of P1P1' =exit pupil of complete microscope.

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  • The position of the diaphragm limiting the pencils proceeding from the object-points is not constant in the compound microscope.

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  • - Entocentric transmission through a microscope objective.

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  • - Hypercentric transmission in a microscope objective.

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  • 13 that the objective's exit pupil P'P1' is portrayed by the positive eyepiece, the image P"P i " limits the pencils P ', double microscope; these inverting prisms permit a convenient adaptation of the instrument to the interpupillary distance of the observer.

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  • - Weak and medium microscope objectives work like photographic objectives in episcopic or diascopic projection; in the microscope, however, the projected image is not intercepted on a screen, but p?

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  • - Ray transfocused for; and all points in it are mission in compound sharply portrayed (a perfect objective microscope with a negabeing assumed).

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  • It follows that the depth of definition of the microscope is in general very trifling.

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  • We can now understand the ray transmission in the compound microscope, shown in fig.

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  • The increase of the inclination of the principal rays, which arises with the microscope, influences the perception of the relief of the object.

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  • Although in the case of the spatial comprehension of a perspective representation experience plays a large part, in observing through a microscope it does not count, or only a little, for the object is presumably quite unknown.

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  • The function n sin u = A, for the microscope, has been called by Abbe the numerical aperture.

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  • THE Physical Theory In order to fully understand the representation in the microscope, the process must be investigated according to the wavetheory, especially in considering the representation of objects or object details having nearly the size of a wave-length.

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  • Abbe applied the Fraunhofer diffraction phenomena to the explanation of the representation in the microscope of uniformly illuminated objects.

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  • If a grating is placed as object before the microscope objective, Abbe showed that in the image there is intermittent clear and dark banding only, if at least two consecutive diffraction spectra enter into the objective and contribute towards the image.

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  • If the illuminating pencil is parallel to the axis of the microscope objective, the illumination is said to be direct.

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  • back focal plane of the objective, can be conveniently seen with the naked eye by removing the eyepiece and looking into the tube, or better by focusing a weak auxiliary microscope on the back focal plane of the objective.

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  • The magnification and magnifying number which are most necessary for a microscope with an objective of a given aperture can then be calculated from the formulae: V4 = 2A tan 4'/X; N4 = 2Al tan 4'/A.

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  • Soc., 1882, p. 463) we have the following table for the limits of the magnification numbers, for various microscope objectives, µ = o ooi mm.: A=nsinu.

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  • The power of the microscope is thus represented by presupposing day-light with a wave-length of 550 Au.

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  • the exit pupil of the microscope is about 0.04 in.

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  • With the .orthogonal arrangement for illuminating and observing the beam of light traverses an extremely fine slit through a well-corrected system, whose optic axis is perpendicular to the axis of the microscope; the system reduces the dimensions of the beam to about 2 to 4 in the focal plane of the objective.

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  • Very large apertures occur in strong microscope objectives, and hence the two conditions are not compatible.

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  • A well-corrected microscope objective with a wide aperture therefore can only represent, free from aberrations, one object-element situated on a definite spot on the axis.

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  • By experiment Abbe proved that old, good microscope objectives, which by mere testing had become so corrected that they produced usable images, were not only free from spherical aberrations, but also fulfilled the sine-condition, and were therefore really aplanatic systems.

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  • In systems employed for visual observation (to which class the microscope belongs) the red and blue rays, which include the physiologically most active part of the spectrum, are combined; but rays other than the two selected are not united in one point.

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  • The first real improvement in the microscope objective dates from 1830 when V.

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  • Selligue had no particular comprehension of the problem, for his achromatic single systems were simply telescope objectives corrected for an infinitely distant point, and were placed so that the same surface was turned towards the object in the microscope objective as in the telescope objective; although contrary to the telescope, the distance of the object in the microscope objective is small in proportion to the distance of the image.

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  • He had recognized that the good operation of a microscope objective depended essentially upon the size of the aperture, and he therefore endeavoured to produce systems with wide aperture and good correction.

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  • The most perfect microscope objective was invented by E.

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  • Its purpose in a microscope is by means of narrow cones of rays to represent at infinity the real magnified image which the objective produces.

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  • P"P" = Ramsden's circle, or exit-pupil of whole microscope.

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  • ID on the eyepiece the total magnification of the microscope is obtained.

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  • Illuminating Systems Most microscopic observations are made with transmitted light; an illuminating arrangement is therefore necessary, and as the plane of the object is nearly always horizontal or only slightly inclined, the illuminating rays must be directed along the optical axis of the microscope.

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  • It =; L 1 = front lens is simpler to place an illuminating O of microscope; lens in front of the source of light so PP =diaphragm.

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  • This concentration is most easily produced by sliding or revolving diaphragms. A series of holes of different sizes perforate a revolving disk below the stage plate at an equal radial distance from the axis of the disk, so that the holes can be brought under the preparation in turn, the centre of the diaphragms always being a continuation of the optical axis of the microscope.

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  • Hence a condenser, for lighting with very oblique cones, must have about the same aperture as the objective, and therefore be of very wide aperture; they therefore closely resemble microscope objectives in construction.

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  • Especially powerful achromatic condensers are really only magnified microscope objectives, with the difference that they are not corrected for the thickness of the cover slip, but for the thickness of the glass on which the object is placed.

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  • For exceptionally accurate work microscope objectives are sometimes used as condenser systems. When using immersion objectives, an immersion condenser must also be used if rays of extreme obliquity are wanted, for, in consequence of the total reflections, rays can only come from the upper plane surface of the condenser, which have not a larger inclination to the axis than about 41°, varying according to the refractive index of the glass.

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  • Binocular Instruments The stereoscopic microscope is the most suitable for finding out the space taken up by the separate parts of a preparation.

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  • One way of receiving a stereoscopic impression through a microscope is by fixing an apparatus as directly as possible above the last lens of the microscopic objective, which divides the rays passing out and directs half into each eyepiece.

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  • The newest form of a stereoscopic microscope resembles the oldest in so far as two completely separate microscopes are used.

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  • In the oldest microscope by Cherubin d'Orleans the observer receives a pseudoscopic impression in consequence of the reversed image.

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  • The microscope is only intended for slight magnifications.

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  • A microscope for two eyes can also be obtained by employing the Abbe stereoscopic eyepiece.

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  • It is brought about by placing special semicircular diaphragms in the plane of the exit pupil of the microscope.

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  • Mechanical Arrangements Although the optical system is the first consideration in a microscope, the system is valueless if the fittings do not allow its correct use.

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  • 60, Plate, the microscope is seen to consist of the heavy metal foot A, which rests on the table at three points.

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  • The whole microscope is fitted to this foot.

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  • A fine adjustment is also necessary, in order to perform conveniently and with certainty the slight motion of the microscope in relation to the object.

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  • Almost all are such that the whole microscope tube is raised or sunk by the mechanism of the fine adjustment, and not only the objective.

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  • - Stephenson'S Binocular Microscope Fig.

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  • - THE Demonstration Microscope (Swift) .

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  • 59.-Greenough'S Binocular Microscope (Zeiss).

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  • 61.-Petrographical Microscope (Zeiss).

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  • An essential in all rough and fine adjustments is that the motion must always be parallel to the optical axis of the microscope, so that the same point in the object remains in the centre of the field.

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  • It is only rarely necessary to arrange the preparation really horizontal; and for easy observation, especially when it will take a long time, it is of great assistance if the microscope can be inclined, so that the observations can be made in a natural position.

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  • The apparatus for inclining the microscope is chiefly such that the microscope can be placed in all positions between the vertical and the horizontal.

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  • The horizontal position is sometimes necessary if photographs are to be taken by the microscope.

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  • The microscope stands described above can be used for the greater number of the naturalist's experiments.

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  • The petrographical microscope is shown in fig.

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  • In order to determine the refractive index when the thickness of the crystal is known, or the thickness of the crystal when the index is known, a fine adjustment A makes it possible to measure exactly the changes in the length of the microscope.

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  • To obviate mistakes the optical axis of the microscope must coincide with the revolving axis of the plate, and the revolving plate has a central position C to keep this condition fulfilled.

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  • The image produced by the microscope objective M in its back focus plane is then observed through a supplementary microscope.

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  • The objective of this supplementary microscope, the Bertrand lens, can be applied through a window I at the lower end of the inner tube K.

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  • By using a rack and pinion movement L the supplementary microscope can be adjusted for the images.

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  • After the microscope has been so adjusted that the image of the object to be measured falls exactly in the plane of the cross threads, the object is moved by the micrometer until one edge of the object is exactly covered by a thread.

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  • When determining the magnification the microscope must be used under exactly the same conditions: neither the length of the tube nor the focal length of the objective may be altered.

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  • If, as before, an objective micrometer is placed below the microscope in the place of the object, and the size of a special micrometer-interval is drawn on the same board, then the actual size of the object can be ascertained.

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  • THE Testing Of The Microscope The excellence of a microscope objective depends on its definition and its resolving power.

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  • A diaphragm with a very narrow hole is placed on the stage, and the microscope sharply focused on the edges of the hole.

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  • The illuminating mirror is turned aside and a graduated scale is laid on the foot of the microscope.

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  • Strong systems produce in the proximity of their back focal plane an image of the scale, which can be inspected with a weak auxiliary microscope, and the length of the visible part of the graduation determined.

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  • With weak systems no auxiliary microscope is necessary, the eyepiece being removed and the scale viewed directly in the tube.

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  • Through this hole the points of the metal plates b can be observed by total reflection on the surface c. The apertometer is laid on the stage, so that the hole lies in the axis of the microscope, and the hole is sharply focused.

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  • With strong systems the vanishing of the points is observed with an auxiliary microscope, formed by means of the inner tube.

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  • The magnification of a microscope is determined from the focal lengths of the two optical systems and the optical tube length, for N = 250 A/fi'f2 To determine the optical tube length 0, it is necessary to know the position of the focal planes of the objective and of the ocular.

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  • If one focuses an auxiliary microscope, carried in the inner tube, on the image situated in the back focal plane of the objective of a distant object, and then on the dust particles lying on a slide pressed against the end of the outer tube, the displacement of the auxiliary microscope gives the distance of the back focal plane of the objective from the end of the outer tube.

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  • An auxiliary microscope is now focused first on the image of a distant object and then on the plane of the edge of the setting.

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  • These are the dimensions necessary for determining the magnification of the microscope, viz.

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  • Carpenter, The Microscope and its Revelations (8th ed.

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  • Hogg, The Microscope (15th ed., 1898); H.

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  • van Heurck, The Microscope (Eng.

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  • Here it need only be said that the masses of vegetable substance, more or less carbonized and chemically altered, of which coal is composed, frequently contain cells and fragments of tissue in a condition recognizable under the microscope, as for example spores (sometimes present in great quantities), elements of the wood, fibres of the bark, &c. These remnants, however, though interesting as revealing something of the sources of coal, are too fragmentary and imperfect to be of any botanical importance.

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  • In nature, clays are rarely free from foreign ingredients, many of which can be detected with the unaided eye, while others may be observed by means of the microscope.

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  • bini, two at a time, and oculi, eyes) was originally an adjective used to describe things adapted for the simultaneous use of both eyes, as in "binocular vision," "a binocular telescope or microscope"; now "a binocular" is used as a noun, meaning a binocular microscope, a field-glass, &c.

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  • The first binocular microscope was invented by the previously mentioned Father.

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  • Riddell (1807-1867) devised his binocular microscope, which contained the essentials of Wheatstone's pseudoscope.

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  • led to the construction of a non-stereoscopic binocular microscope.

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  • of Alfred Nachet, who in 1853, and subsequently in 1863, brought forward two forms of binocular microscope.

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  • The earliest stages of the development of the binocular microscope had been always confined to those instruments with one objective, in the immediate neighbourhood of which the systems for dividing the pencil were placed.

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  • The newest form of the binocular microscope is very similar to the oldest form in which two completely separated be made of A.

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  • The image, despite the spherical aberration, was by far superior to any existing microscope made by his contemporaries.

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  • The older text books called them ' slipper animalcules ' as with careful study under a compound microscope they do look like a slipper.

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  • Under the microscope, dark-ground illumination reveals the details of one of the darker anthers and its filament.

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  • numerical aperture The numerical aperture of a microscope objective is a measure of its ability to resolve fine specimen detail.

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  • Apart from insects there are some other aquatic arthropods that are worth a closer examination under the microscope.

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  • atomic force microscope, nanometer-sized holes will be created on various surfaces.

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  • Their work in the field of forensic ballistics, with the comparison microscope, brought fair justice at murder trials.

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  • The equid bones will be measured and examined for traces of human butchery under a low power binocular microscope.

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  • The sensor itself is an atomic force microscope cantilever.

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  • The mitotic index is the fraction of cells in a microscope field which contain condensed chromosomes.

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  • Lots of these collagen fibrils are bound together to form collagen fibrils are bound together to form collagen fibers that easily can be seen with a light microscope.

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  • compensator plate has been modified by Prior to allow manual adjustment of the angle, while it is still inserted in the microscope.

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  • compound light microscope.

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  • In 1846 Darwin bought a compound microscope because of his need for higher magnifications (shown left ).

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  • confocal microscope, however, makes optical sections through a whole intact subject.

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  • If urate crystals can be seen in the fluid under a microscope, you have gout.

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  • Some years ago I examined a smear of metal polish under the microscope and found it contained many diatoms.

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  • Koch discovered that methyl violet dye showed up the septicaemia germ under a microscope by staining it.

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  • Its basis, however, when viewed under the microscope, is generally quite earthy; but sometimes it exhibits a decidedly crystalline structure.

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  • electron microscope are these " ghost " mast cells seen.

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  • The image was acquired using electron holography in a field emission gun transmission electron microscope.

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  • The image was taken on a scanning electron microscope.

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  • They can only be seen using an electron microscope.

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  • electron microscope fitted with an energy dispersive X-ray analyzer.

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  • A picture of a high resolution electron microscope, which is able to see atoms, is shown in Fig.

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  • If there is, HERA, the most powerful electron microscope in the world, may be the first to know.

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  • electron microscope images are needed for closely detailed examination.

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  • electron microscope picture of a small part of the rock showing tube-like structures.

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  • electron microscope facility in the Bute Medical Building.

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  • electron microscope study of the groove profiles may help isolate lines engraved with different tools.

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  • electron microscope photographs of diatoms ).

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  • The image was acquired using electron holography in a field emission gun transmission electron microscope.

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  • etch pit, large enough to be visible under low magnification in the optical microscope.

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  • examine under a microscope at low power i.e. 10 x 4 or 10 x 10.

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  • eyepiece adaptor to mount it on my compound microscope.

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  • Method 2: SLR lens and microscope eyepiece removed.

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  • Lots of these collagen fibrils are bound together to form collagen fibers that easily can be seen with a light microscope.

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  • field gunge was acquired using electron holography in a field emission gun transmission electron microscope.

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  • High extinction polarizing filters for microscopy are preferable for polarization studies (a microscope dealer's own brand should be of good quality ).

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  • high-powered microscope.

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  • Under the microscope, using dark-ground illumination, a single pollen covered filament can be seen to have spiked ridges.

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  • Have a go at building your own LED microscope illuminator with a simple battery supply which lasts hours!

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  • What one sees under the microscope is much better than the photographic image.

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  • indentation left in the test material is measured with a microscope.

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  • invention of the compound microscope and suggests immersion lens.

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  • led microscope illuminator with a simple battery supply which lasts hours!

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  • Szilard's ideas included the linear accelerator, cyclotron, electron microscope, and nuclear chain reaction.

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  • With a microscope it is possible to obtain even higher magnifications.

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  • mica flakes from this area of the rock and study under the microscope.

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  • X-ray microanalysis and imaging The microscope is equipped with an Oxford Instruments ISIS microanalysis system.

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  • The measurement of specimen size with a microscope is normally made by using an eyepiece micrometer.

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  • Integrated circuit technology has allowed manufacturers to produce " smart " microscopes that incorporate microprocessors into the microscope stand.

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  • The colors appear under the polarized light microscope that earth scientists use to identify rock crystals.

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  • The lenses from an old pair of Polaroid sunglasses may be used to make a simple polarizing microscope.

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  • The image was taken on a scanning electron microscope.

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  • microscope at a magnification of x 400.

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  • SCULLY: Actually, it's an image created by what's called a confocal microscope.

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  • The float of each sample was studied under a low power binocular microscope.

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  • Just prior to his visit, I had acquired a Wild inverted plankton microscope with phase.

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  • Using the sharp tip of an atomic force microscope, nanometer-sized holes will be created on various surfaces.

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  • Using an optical microscope Wembley Stadium would look like a blurred blob.

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  • Images were taken using a CCD camera attached to the eyepiece tube of a stereo microscope using a x1 paired objective with no eyepiece.

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  • microscope eyepiece.

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  • microscope slide without damaging the structure of the mold.

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  • Only with the use of an electron microscope are these " ghost " mast cells seen.

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  • The tutorial initializes with a cut-away schematic diagram of a reflected light fluorescence microscope appearing in the window.

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  • Large feathers are easy to study under a hand lens or low power stereo microscope.

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  • The image was acquired using electron holography in a field emission gun transmission electron microscope.

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  • They put out tubes holding cuttings of milkweed stems with two leaves, whole potted milkweed plants, and microscope slides coated with glycerin.

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  • monocular microscope 's eyepiece.

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  • The Victorians used to enjoy creating silver under the microscope from silver nitrate in solution.

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  • Microscope: Bausch & Lomb monocular, 10x ocular, 10x ocular, 4x, 10x and 40x objectives.

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  • optics of the microscope may improve the results.

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  • Electron microscope image of plant cell organelles Photo: Dr. Alison Baker, University of Leeds.

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  • peek down the microscope and to try out experiments for yourself.

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  • Nevertheless they sufficed to attract the eye, when the whole petiole was viewed as a transparent object beneath the microscope.

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  • See the scanning electron microscope photomicrograph and figures below.

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  • Sierra Pole Creek To show photomicrographs with the Swift microscope, we skip ahead to May of 2001.

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  • photomicrographs in the article were taken using a Leitz SM-Pol microscope equipped with a Nikon Coolpix 4500 digital camera.

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  • Anything you see can become a superb photomicrograph by aligning your camera to capture the image coming out of the monocular microscope's eyepiece.

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  • polarized filters in the microscope.

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  • polarizew melting points of most liquid crystals make them easy to study under the polarizing microscope.

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  • PVC pipe coupling, which allows me to stick it on the end of the microscope tube.

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  • The tipo piu comune is the optical microscope, nel quale l'esame of the object viene fatto in luce visibile... .

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  • Features not resolvable using the light microscope are also found.

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  • To use a reticle on the stage, place it carefully on a microscope slide.

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  • Seen under the microscope these stipules have small droplet of what I assume to be sugary sap in the hollow underneath.

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  • scanning electron microscope.

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  • schematic drawing of the scanning electron microscope is also provided with a SEM image.

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  • sees under the microscope is much better than the photographic image.

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  • showcaseclass="ex">Showcasing an array of talent, visual styles and social themes that put modern India under the microscope.

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  • You may wish to buy some microscope slide boxes to store permanent preparations which you have made or bought.

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  • small intestine of cats Electron Microscope Image Breed Occurrence There are no specific breed predispositions.

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  • spherical aberration, was by far superior to any existing microscope made by his contemporaries.

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  • Under the microscope, an anther can be seen to have many spherical to ellipsoidal pollen grains on its surface.

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  • stereo microscope.

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  • stereoscopic microscope.

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  • At higher magnifications, using a scanning electron microscope, fatigue striations can be observed (Figure 7 ).

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  • submicron resolution using a novel X-ray microscope.

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  • The simple fact is that coverslip thickness is important in quality microscope imaging using objectives of moderate to higher powers.

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  • time-lapse microscope movies.

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  • The electron microscope image shows sections of a lead zirconate titanate (PZT) plate diced using the CVL.

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  • The electron microscope made this possible by playing the role of a " laboratory totem " for a growing tribe of molecular biologists.

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  • transformer mounted inside the mahogany box that housed the microscope.

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  • transmission electron microscope.

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  • A laboratory technician places some of the fluid on a slide and looks for monosodium urate crystals under a microscope.

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  • villusre 1: healthy villi of the small intestine (as seen under the microscope ).

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  • visible under the microscope.

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  • The children are experts at isolating the tiny zooplankton with a pipette and we see some great examples of copepods under the microscope.

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  • The beginning of definite knowledge on the phenomenon of fermentation may be dated from the time of Antony Leeuwenhoek, who in 1680 designed a microscope sufficiently powerful to render yeast cells and bacteria visible; and a description of these organisms, accompanied by diagrams, was sent to the Royal Society of London.

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  • yeasts was by studying morphological differences with the aid of the microscope.

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  • Quekett in his Treatise on the Microscope ascribes to Ramsden the practical introduction of the spider web in micrometers.

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  • This interpolation can, of course, be accomplished with the aid of a micrometer-microscope whose optical axis is normal to the plate, provided that the plate is mounted on slides which enable the observer to bring the reseau-squares successively under the microscope.

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  • The microscope or viewing telescope is fitted with a spider-line micrometer having two screws at right angles to each other, by means of which readings can be made first on one reseau-line, then on the star, and finally on the opposite reseau-line in both co-ordinates.

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  • The image of a normal reseau-square, as viewed in the microscope, shall exactly coincide with the square formed by the fixed webs - that is to say, the image of the sides of a normal reseau-square shall measure exactly io screw-revolutions.

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  • The excellent manner in which the scales and micrometers are mounted, the employment of a compound microscope for viewing the scales, with its ingeniously arranged and admirably efficient reversing prism, and the perfection of its slow motions for focusing and reading, combine to render this a most accurate and convenient instrument for very refined measures, although too slow for work in which the measures must depend on single pointings in each of two reversed positions of the plate, and where speed of working is essential.

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  • A, in which the motion of the slide which carries the photographic plate is measured entirely by a screw; B, in which that motion is measured by combination of a scale and screw; and C, in which the A F B photographic plate is fixed and the measuring microscope is moved.

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  • In the Potsdam form of this apparatus the micrometer is, for convenience, provided with a motion at right angles to the axis of the screw, and it has been found at the Cape Observatory that the periodic errors in this apparatus do vary very sensibly according as the microscope is directed to a point more or less distant from the measuring screw.

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  • Since the discovery of this fact all measurements have been made in that fixed position of the microscope with respect to the axis of the screw for which the errors of the screw have been determined.

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  • In this way the scale can be viewed by a microscope of much higher magnifying power than can be employed for the photographed spectrum.

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  • The forms of measuring machines of type C, often seen in physical laboratories, should be at once rejected for refined measurements, because it is impossible to construct slides of such perfection that the axis of the microscope will remain absolutely normal to the surface of the plate (assumed to be a plane) throughout the range of measurement.

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  • We have, in fact, in this instrument a combination of types B and C. Even in this apparatus if the slide on which the chariot moves is not perfect (and no slide is perfect), the azimuth of the axis of the microscope is liable to change in the course of movement of the slide, and thus equal spaces on the scale will not be represented by equal spaces on the plate under measurement.

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  • The remedy proposed by Repsold for this proved fault is to cause the whole slide to tilt instead of the microscope only; this should prove a complete remedy.

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  • Vogel and his successors employed one or other form of measuring machine, provided with a microscope having single or close parallel webs which could be successively pointed on the photographed lines of the star spectrum and the lines of the terrestrial spectrum.

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  • The term Cryptogam is archaic, implying a hidden method of reproduction as compared with the obvious method represented by the flower of the Phanerogam; with the aid of a good microscope it is, however, easier to follow the process of fertilization.

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  • When the sieve-tube has ceased to function and the protoplasm, slime strings, and callose have disappeared, the perforations through which the slime strings passed are left as relatively large holes, easily visible in some cases with low powers of the microscope, piercing the sieve.plate.

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  • In some cases it shows, when submitted to a careful examination under the highest powers of the microscope, and especially when treated with reagents of various kinds, traces of a more or less definite structure in the form of a meshwork consisting of a clear homogeneous substance containing numerous minute bodies known as microsomes, the spaces being filled by a more fluid ground-substance.

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  • He was the inventor of the stage-micrometer, and of a form of heliometer; and in 1816 he succeeded in constructing for the microscope achromatic glasses of long focus, consisting of a single lens, the constituent glasses of which were in juxtaposition, but not cemented together.

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  • On the 6th of November in that year he plainly saw the living parasites under the microscope in the blood of a malarial patient, and he shortly afterwards communicated his observations to the Paris Academie de Medecine.

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  • He examined the yeasts under the microscope, and at once saw that the globules from the sound beer were nearly spherical, whilst those from the sour beer were elongated; and this led him to a discovery, the consequences of which have revolutionized chemical as well as biological science, inasmuch as it was the beginning of that wonderful series of experimental researches in which he proved conclusively that the notion of spontaneous generation is a chimera.

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  • At a later period he was one of the leading contributors to the Encyclopaedia Britannica (seventh and eighth editions), the articles on Electricity, Hydrodynamics, Magnetism, Microscope, Optics, Stereoscope, Voltaic Electricity, &c., being from his pen.

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  • 37), in which it is possible most satisfactorily to study in the living animal, by means of the microscope, the course of the blood-stream, and also the reno-pericardial communication.

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  • The capillary tube can be raised or lowered at will by running a magnet outside the tube, and the heights of the columns are measured by a cathetometer or micrometer microscope.

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  • The plant can then be at any time examined under the microscope without injuring the mounted specimen.

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  • In polarized light they show a weak grey colour with a black cross, the arms of which are parallel to the cobwebs in the eyepiece of the microscope and remain stationary when the section is rotated.

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  • Often this felsitic devitrified glass is so fine-grained that its constituents cannot be directly determined even with the aid of the microscope, but chemical analysis leaves little doubt as to the real nature cf the minerals which have been formed.

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  • It is, like milk, an emulsion, and when examined with the microscope is seen to consist of numerous globules suspended in a watery fluid.

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  • The acute bisectrix of the optic axes never deviates from the normal to the basal plane by more than a degree or two, hence a cleavage flake of mica will always show an optic figure in convergent light when placed on the stage of a polarizing microscope.

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  • It consists of a definite contractile sac or sacs lying on the dorsal side of the alimentary canal near the oesophagus, and in preparations of Terebratulina made by quickly removing the viscera and examining them in sea-water under a microscope, he was able to count the pulsations, which followed one another at intervals of 30-40 seconds.

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  • When examined with the microscope, by means of the usual section method, they are seen to consist of a labyrinthine tube lined with peculiar cells, each cell having a deep vertically striated border on the surface farthest from the lumen, as is seen in the cells of some renal organs.

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  • It was not until the 19th century that the microscope, thus early applied by Leeuwenhoek, Malpighi, Hook and Swammerdam to the study of animal structure, was perfected as an instrument, and accomplished for zoology its final and most important service.

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  • The perfecting of the microscope led to a full comprehension of the great doctrine of cell-structure and the establishment of the facts - (r) that all organisms are either, single corpuscles (so-called cells) of living material (microscopic animalcules, &c.) or are built up of an immense number of such units; (2) that all organisms begin their individual existence as a single unit or corpuscle of living substance, which multiplies by binary fission, the products growing in size and multiplying similarly by binary fission; and (3) that the life of a multicellular organism is the sum of the activities of the corpuscular units of which it consists, and that the processes of life must be studied in and their explanation obtained from an understanding of the chemical and physical changes which go on in each.

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  • The study of the ultimate corpuscles of living matter, their structure, development and properties, by the aid of the microscope; exemplified by Malpighi, Hook, Schwann, Kowalewsky.

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  • (see Agassiz, Essay on Classification, 1859), which were as numerous as the professors of zoological science, was necessarily succeeded in the true progress of the science by a period of minuter study in which the microscope, the discovery of embryological histories, and the all-important cell-theory came to swell the stream of exact knowledge.

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  • great school or university, is that of John Vaughan Thompson (1779-1847), an army surgeon, who in 1816 became district medical inspector at Cork, and then took to the study of marine Invertebrata by the aid of the microscope.

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  • The application, unaccountably long delayed, of this principle to the microscope by H.

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  • 4, AB represents the axis of an optical instrument (telescope or microscope), A being a point of the object and B a point of the image.

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  • The statement of the law of resolving power has been made in a form appropriate to the microscope, but it admits also of immediate application to the telescope.

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  • If 2R be the diameter of the objectglass and D the distance of the object, the angle subtended by AP is E/D, and the angular resolving power is given by X/2 D sin a = X/2 R (3) This method of derivation (substantially due to Helmholtz) makes it obvious that there is no essential difference of principle between the two cases, although the results are conveniently stated in different forms. In the case of the telescope we have to deal with a linear measure of aperture and an angular limit of resolution, whereas in the case of the microscope the limit of resolution is linear, and it is expressed in terms of angular aperture.

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  • Stoney, the restriction is often, perhaps usually, violated in the microscope.

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  • So in the microscope there is nothing except lack of light to hinder the visibility of an object however small.

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  • A comparison with the method of a material pointer, attached to the parts whose rotation is under observation, and viewed through a microscope, is of interest.

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  • The limiting efficiency of the microscope is attained when the angular aperture amounts to 180°; and it is evident that a lateral displacement of the point under observation through -IX entails (at the old image) a phase-discrepancy B Q' of a whole period, one extreme ray FIG.

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  • Lockhart Clarke (1817-1880), one of the earliest investigators of nervous pathology, the improvement of the compound microscope had not attained the achromatism, the penetration and the magnification which have since enabled J.

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  • In the mutual behaviour of such cells, toxins, and antitoxins, and again of microbes themselves, we may demonstrate even on the field of the microscope some of the modes of such actions, which seem to partake in great measure at any rate of a chemical quality (agglutinins, coagulins, chemotaxis).

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  • He also made great use of the simple dark chamber for his optical experiments with prisms, &c. Joseph Priestley (1772) mentions the application of the solar microscope, both to the small and portable and the large camera obscura.

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  • The first binocular magnifying glass or simple microscope (German, Lupe) was devised by J.

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  • In fact the uniformity of brass and bell-metal is only superficial; if we adopt the methods described in the article Metallography, and if, after polishing a plane face on a bit of gun-metal, we etch away the surface layer and examine the new surface with a lens or a microscope, we find a complex pattern of at least two materials.

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  • It is, however, not possible to detect the copper in the silver by means of the microscope.

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  • Solid solutions are probably very common in alloys, so that when an alloy of two metals shows two constituents under the microscope it is never safe to infer, without further evidence, that these are the two pure metals.

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  • The chilling stereotypes the structure existing in the ingot at the moment it was withdrawn from the furnace, and we can af terwards study this structure by means of the microscope.

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  • a microscope cover-glass, held close to the eye and inclined at an angle of 45° to the horizon, one can See the images of objects in front, formed by reflection from the surface of the glass, and at the same time one can also see through the transparent glass.

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  • The word is also used as a unit of linear measurement of the magnifying power of a lens or microscope.

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  • means of measuring the focal point were provided; symmetrical motion was given to the slides; scales on each slide were provided instead of screws for measuring the separation of the segments, and both scales were read by the same micrometer microscope; a metallic thermometer was added to determine the temperature of the scales.

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  • a is the eye-piece, b the handle for moving the segments, c the micrometer microscope for reading the scales and scale micrometer, d the micrometer readers of the position and declination circles, e the handle for rotating the large wheel E which carries the screens.

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  • (d) The scales are made of iridio-platinum instead of silver, and the magnifying power of the reading microscope is increased fourfold (viz.

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  • A special microscope is introduced for determining the division errors of the scales.

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  • Lissajous also obtained the figures by aid of the vibration microscope, an instrument which he invented.

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  • Instead of a mirror the second fork carries a bright point on one prong, and the microscope is focused on this.

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  • If both forks vibrate, an observer looking through the microscope sees the bright point describing Lissajous figures.

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  • One prong of the fork carries a microscope objective, wart of a vibration microscope, of which the eyepiece is fixed at the back of the clock and the Lissajous figure FIG.

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  • The energy of this fork with a given amplitude of vibration could be calculated from its dimensions and elasticity, and the amplitude was observed by measuring with a microscope the line into which the image of a starch grain on the prong was drawn by the vibration.

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  • The development of the compound microscope rendered possible the accurate study of their life-histories; and the publication in 1851 of the results of Wilhelm Hofmeister's researches on the comparative embryology of the higher Cryptogamia shed a flood of light on their relationships to each other and to the higher plants, and supplied the basis for the distinction of the great groups Thallophyta, Bryophyta, Pteridophyta and Phanerogamae, the last named including Gymnospermae and Angiospermae.

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  • In the verification of weights and measures a margin of error is permitted to manufacturers and scale-makers, as it is found to be impossible to make two weights, or two measures, so identical that between them some difference may not be found either by the balance or the microscope.

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  • As rotifers are common in ponds, the first workers with the microscope observed them repeatedly, the first record being that of John Harris in 1696, who found a Bdelloid in a gallipot that had been standing in his window.

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  • The microscope shows that the neighbouring filaments are held together by patches of cilia, called " ciliated junctions," which interlock with one another just as two brushes may be made to do.

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  • His name is best known for the improvements he effected in the mirrors of reflecting telescopes and especially in the construction of the microscope.

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  • Under the microscope the ovary is seen to be covered by a FIG.

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  • Under the microscope cocoon silk presents the appearance (fig.

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  • The silk of the various species of Antheraea and Attacus is also thicker and stronger at the centre of the reeled portion than towards its extremities; but the diameter is much greater than that of common silk, and the filaments under the microscope (fig.

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  • The rod-like appearance of silk and its absence of markings under the microscope are also easily recognizable features of the fibre.

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  • On cutting across a grain of rice and examining it under the microscope, first the flattened and dried cells of the husk are seen, and then one or two layers of cells elongated in a direction parallel to the length of the seed, which contain the gluten or nitrogenous matter.

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  • Sorby and, later, Abbe, designed instruments on the same principle to be used in connexion with the microscope.

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  • The needle b is then substituted for a, there being now no needle in the clamp attached to the microscope arm, and the difference between the reading now obtained and the dip, together with the weight added to the needle, gives the product of the moment of the needle b into the earth's total force.

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  • In some solutions they are visible under a good microscope.

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  • Among those directly visible to the microscope are oil drops, often coloured (Uredineae) crystals of calcium oxalate (Phallus, Russula), proteid crystals (Mucor, Pilobolus, &c.) and resin (Polyporei).

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  • Invisible to the microscope, but rendered visible by reagents, are glycogen, Mucor, Ascomycetes, yeast, &c. In addition to these cell-contents we have good indirect evidence of the existence of large series of other bodies, such as proteids, carbohydrates, organic acids, alkaloids, enzymes, &c. These must not be confounded with the numerous substances obtained by chemical analysis of masses of the fungus, as there is often no proof of the manner of occurrence of such bodies, though we may conclude with a good show of probability that some of them also exist preformed in the living cell.

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  • About fifty species of Saccharomyces are described more or less completely, but since many of these cannot be distinguished by the microscope, and some have been found to develop physiological races or varieties under special conditions of - ?u growth, the limits are still far too ill-defined for complete ep botanical treatment of the genus.

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  • Constitution of Iron and Steel.-The constitution of the various classes of iron and steel as shown by the microscope explains readily the great influence of carbon which was outlined in §§ 2 and 3.

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  • Some species are minute filamentous plants, requiring the microscope for their detection; others, like Lessonia, are of considerable bulk, or, like Macrocystis, of enormous length.

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  • In point of size the largest cannot rival the larger Brown Algae, while the majority require the aid of the microscope for their investigation.

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  • These passages certainly prove that Bacon had very nearly, if not perfectly, arrived at theoretical proof of the possibility of constructing a telescope and a microscope; but his writings give no account of the trial of an actual telescope, nor any detailed results of the application of a telescope to an examination of the heavens.

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  • The earlier arrangement of two lenses of the Huygenian eye-piece (see Microscope) having foci with ratio of 3 to I, gives a fairly large flat field of view approximately free from distortion of tangential lines and from coma, while the Mittenzw ?

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  • In the Ramsden eyepiece (see Microscope) the focal lengths of the two piano-convex lenses are equal, and their convexities are turned towards one another.

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  • If we now attach to the polar axis a graduated circle D D, called the" hour circle,"of which the microscope or vernier R reads o h when the declination axis is horizontal, we can obviously read off the hour angle from the meridian of any star to which the telescope may be directed at the instant of observation.

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  • This investigation is also memorable because he detected the minute sugar-crystals in the roots by the help of the microscope, which was thus introduced as an adjunct to chemical inquiry.

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  • Any divergence or collapse of the gold-leaf can be viewed by a microscope through an aperture in the side of the case.

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  • If then the strip of gold-leaf is raised or lowered in potential it moves to or from the plate P, and its movement can be observed by a microscope through a hole in the side of the box.

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  • divisions of the micrometer scale in the eye-piece of the microscope, 54 divisions being equal to one millimetre.

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  • Several green-coloured beetles are, on account of their colour, used as adulterants to cantharides, but they are very easily detected by examination with the eye, or, if powdered, with the microscope.

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  • The micro-organism giving rise to this disease generally appears in the form of small jointed rods and tangled masses under the microscope.

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  • The following may be regarded as typical: - (t) Largest aperture; necessary corrections are - for the axis point, and sine condition; errors of the field of view are almost disregarded; example - highpower microscope objectives.

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  • Abbe succeeded in computing microscope objectives free from error of the axis point and satisfying the sine condition for several colours, which therefore, according to his definition, were " aplanatic for several colours "; such systems he termed " apochromatic."

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  • This Is Produced In The Same Amount, But In The Opposite Sense, By The Oculars, Which Are Used With These Objectives (" Compensating Oculars "), So That It Is Eliminated In The Image Of The Whole Microscope.

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  • The Best Telescope Objectives, And Photographic Objectives Intended For Three Colour Work, Are Also Apochromatic, Even If They Do Not Possess Quite The Same Quality Of Correction As Microscope Objectives Do.

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  • The fungus is very small in size, and under the microscope appears slightly whitish or colourless.

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  • Until about 1725 the belief was very prevalent that cochineal was the seed of a plant, but Dr Martin Lister in 1672 conjectured it to be a kind of kermes, and in 1703 Antony van Leeuwenhoek ascertained its true nature by aid of the microscope.

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  • The presence in the root of starch, resin and oxalate of lime is revealed by the use of the microscope.

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  • THE Study Of Bacteria The general advances which have been made of late years in the study of bacteria are clearly brought to mind when we reflect that in the middle of the 19th century these organisms were only known to a few experts and in a few forms as curiosities of the microscope, chiefly interesting for their minuteness and motility.

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  • nutri' nt gelatine is fixed under the microscope and kept at constant temperature, a curve of growth can be obtained recording the behaviour during many hours or days.

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  • The microscope magnifies the distance traversed as well as the organism, and although a bacterium which covers 9 - ro cm.

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  • (i) the discovery of a bacterium in the affected tissues by means of the microscope; (2) the obtaining of the bacterium in pure culture; and (3) the production of the disease by inoculation with a pure culture.

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  • The process is of course observed by means of the microscope, but the clumps soon settle in the fluid and ultimately form a sediment, leaving the upper part clear.

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  • The discovery of the microscope carried the refutation further.

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  • In "frilling" or "frilled structure" the folds have still smaller amplitude, and in many highly corrugated rocks minute folds are observable with the microscope that do not appear to the unaided eye.

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  • The ovary adheres firmly to the seed in the interior, so that on examining a longitudinal section of the grain by the microscope the outer layer is seen to consist of epidermal cells, of which the uppermost are prolonged into short hairs to cover the apex of the grain.

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  • He greatly improved both the telescope and microscope.

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  • The invention of the microscope, attributed to Galileo by his first biographer, Vincenzio Viviani, does not in truth belong to him.

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  • Such an instrument was made as early as 1590 by Zacharias Jansen of Middleburg; and although Galileo discovered, in 1610, a means of adapting his telescope to the examination of minute objects, he did not become acquainted with the compound microscope until 1624 when he saw one of Drebbel's instruments in Rome, and, with characteristic ingenuity, immediately introduced some material improvements into its construction.

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  • C. Stokes, The Microscope (Detroit, 1887-1888); C. Zelinka, Zeitschr.

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  • MICROSCOPE (Gr.

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  • A simple microscope consists of a single positive lens, or of a lens combination acting as a single lens, placed between the eye and the object so that it presents a virtual and enlarged image.

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  • The compound microscope generally consists of two positive lens systems, so arranged that the system nearer the object (termed the objective) projects a real enlarged image, which occupies the same place relatively to the second system (the eyepiece or ocular) as does the real object in the simple microscope.

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  • Convex glass lenses were first generally used to assist ordinary vision as " spectacles "; and not only were spectacle-makers the first to produce glass magnifiers (or simple microscopes), but by them also the telescope and the compound microscope were first invented.

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  • During the Thirty Years' War the simple microscope was widely known.

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  • Antony van Leeuwenhoek appears to be the first to succeed in grinding and polishing lenses of such short focus and perfect figure as to render the simple microscope a better instrument for most purposes than any compound microscope then constructed.

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  • At that time the " compass " microscope was in use.

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  • Early opticians and microscopists gave their chief attention to the improvement of the simple microscope, the principle of which we now explain.

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  • Simple Microscope Position and Size of the Image.

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  • When the details are no longer recognizable by the unaided eye, the magnifying glass or the simple microscope is necessary.

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  • As a rule large magnification is not demanded from the former, but a larger field of view, whilst the simple microscope should ensure powerful magnification even when the field is small.

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  • The simple microscope enlarges the angle of vision, and does not tire the eye when it is arranged so that the image lies in the farthest limit of distinct vision (the punctum remotum).

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  • Since H' P = F 0, = y, from the focal length of the simple microscope, the visual angle w' is given by tan w'/y=I/f'=V, (I) in which f', = H' F', is the image-side focal length (see Lens).

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  • In most cases the number of " diameters " of the simple microscope is required; i.e.

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  • the ratio between the apparent sizes of the object when observed through the microscope and when viewed by the naked eye.

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  • Since this value for the distance of distinct vision is only conventional, it is understood that the capacity of the simple microscope given in (2) holds good only for eyes accustomed to examine small objects io in.

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  • The magnification, resulting from the simple microscope of i in.

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  • From this it appears that each observer obtains specific advantages from one and the same simple microscope, and also the individual observer can obtain different magnifications by either using different accommodations, or by viewing in passive accommodation.

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  • The simple microscope permits such vision.

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  • Triplets are employed when the focal length of the simple microscope was less than in.

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  • To an achromatic collective lens, which is turned towards the object, a dispersive lens is combined (this type to a certain extent belongs to the compound microscope).

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  • Compound Microscope The view held by early opticians, that a compound microscope could never produce such good images as an instrument of the simple type, has proved erroneous; and the principal attention of modern opticians has been directed to the compound instrument.

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  • Although we now know how the errors of lenses may be corrected, and how the simple microscope may be improved, this instrument remains with relatively feeble magnification, and to obtain stronger magnifications the compound form is necessary.

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  • A microscope objective being made in essentially the same way as a simple microscope, and the front focus of the compound system being situated before the front focus of the objective, the magnification due to the simple system makes the free object distance greater than that obtained with a simple microscope of equal magnification.

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  • Moreover, this distance between the object and eye is substantially increased in the compound microscope by the stand; the inconveniences, and in certain circumstances also the dangers, to the eye which may arise, for example by warming the object, are also avoided.

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  • This permits researches which are impossible with the simple microscope.

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  • For example, the real image may be recorded on a photographic plate; it may be measured; it can be physically altered by polarization, by spectrum analysis of the light employed by absorbing layers, &c. The greatest advantage of the compound microscope is that it represents a larger area, and this much more completely than is possible in the simple form.

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  • The simple microscope is subject to either limitation.

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  • As we shall see later, one of the principal functions of the microscope objective is the representation with wide pencils.

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  • In that case, however, in the compound microscope a small object may always be represented by means of wider pencils, one of the foci of the objective (not of the collective system) being near it.

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  • In 1646 Fontana described a microscope which had a positive eyepiece.

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  • The development of the compound microscope essentially depends on the improvement of the objective; but no distinct improvement was made in its construction in the two centuries following the discovery.

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  • A microscope, using concave mirrors, was proposed in 1672 by Sir Isaac Newton; and he was succeeded by Barker, R.

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  • thick, called the cover-slip. If we consider the production of the image of an object of this kind by the two positive systems of a compound microscope shown in fig.

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  • Weak and strong microscope objectives act differently.

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  • When forming an image by a microscope objective it often happens that the transparent media bounding the system have different optical properties.

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  • The image viewed through the eyepiece appears then to the observer under the angle w", and as with the single microscope tan w" = I /f 2 ' (4) where f' 2 is the image-side focal length of the eyepiece.

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  • - Ray transmission in compound microscope with a positive ocular.

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  • P"P 1 " = exit pupil of complete microscope.

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  • To obtain the magnification of the complete microscope we must combine the objective magnification M with the action of the eyepiece.

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  • If we replace y' in equation (4) by the value given by (3), we obtain tan w"/ y i/f2"=V, (5) the magnification of the complete microscope.

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  • The magnification is also expressed as the ratio of the apparent size of the object observed through the microscope to the apparent size of the object seen with the naked eye.

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  • If this value of y be inserted in equation (5), we obtain the magnification number of the compound microscope N =tan w"/ tan w =Ol/f i 'f 2 ' =Vl.

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  • As with the simple microscope, different observers see differently in the same compound microscope; and hence the magnification varies with the power of accommodation.

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  • The image produced by a microscope formed of two positive systems (fig.

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