The top drawer contained the usual assortment of pens, pencils and paperclips.
Graphite is used for the manufacture of pencils, dry lubricants, grate polish, paints, crucibles and for foundry facings.
The massive graphite is very easily machined and is widely used for electrodes, dynamo brushes, lead pencils and the like.
Copying-ink pencils should not be used, as water will wash away the writing.
Other articles of manufacture are leather, tobacco, porcelain, cement, spirits, lead pencils (Nuremberg), plate-glass, sugar, matches, aniline dyes, straw hats and baskets.
They are now chiefly valued for the hair, that of the European badger being used in the manufacture of the best shaving-brushes while the softer hair of the American species is employed for the same purpose, and also for painters' pencils, and the fur is used for articles of ladies' apparel and trimmings.
Berlin and Mainz are celebrated for the manufacture of furniture; Bavaria for toys; the Black Forest for clocks; Nuremberg for pencils; Berlin and Frankfort-on-Main for various perfumes; and Cologne for the famous eau-de-Cologne.
The mere size of the apparent field of view depends upon obtaining the oblique pencils of light emerging from it to cross the axis at the great possible angle, and to this end the presence of a field-lens is indispensable, which is separated from the eye-lens by a considerable interval.
The larges c opening of the pencils, which take part in the reproduction of 0, i.e.
The existence of an optical system, which reproduces absolutely a finite plane on another with pencils of finite aperture, is doubtful; but practical systems solve this problem with an accuracy which mostly suffices for the special purpose of each species of instrument.
Other important branches of industry are: - the manufacture of chemicals at Prague and Aussig; pencils at Budweis; musical instruments at Graslitz and SchOnbach; paper, leather, dyeing and calicoprinting.
Describing the forests of the Manyema country, west of Lake Tanganyika, David Livingstone wrote:" Into these [primeval forests] the sun, though vertical, 'cannot penetrate, excepting by sending down at mid-day thin pencils of rays into the gloom.
Furth is the seat of several important industries; particularly, the production of chromolithographs and picture-books, the manufacture of mirrors and mirror-frames, bronze and gold-leaf wares, pencils, toys, haberdashery, optical instruments, silver work, turnery, chicory, machinery, fancy boxes and cases, and an extensive trade is carried on in these goods as also in hops, metals, wool, groceries and coal.
In the Mediterranean region occur Cupressus sempervirens, Pinus Pinea (stone pine), species of juniper, Cedrus atlantica, C. Libani, Callitris quadrivalvis, Pinus montana, &c. Several conifers of economic importance are abundant on the Atlantic side of North America - Juniperus virginiana (red cedar, used in the manufacture of lead pencils, and extending as far south as Florida), Taxodium distichum (swamp cypress), Pinus rigida (pitch pine), P. mitis (yellow pine), P. taeda,P. palustris, &c. On the west side of the American continent conifers play a still more striking role; among them are Chamaecyparis nutkaensis, Picea sitchensis, Libocedrus decurrens, Pseudotsuga Douglasii (Douglas fir), Sequoia sempervirens, S.
Virginiana, of North America is employed instead for pencils and cigar-boxes.
A method of generating conics essentially the same as our modern method of homographic pencils was discussed by Jan de Witt in his Elementa linearum curvarum (1650); but he treated the curves by the Cartesian method, and not synthetically.
When the shortest distance obtained by the highest strain of accommodation is insufficient to recognize small objects, distinct vision is possible at even a shorter distance by placing a very small diaphragm between the eye and the object, the pencils of rays proceeding from the object-points, which otherwise are limited by the pupils of the eye, being thus restricted by the diaphragm.
The object is then projected with such acute pencils on the plane focused for, in this case on the plane on which the eye can just accommodate itself, that the circle of confusion arising there is still so small that it is below the limit of angular visual distinctness and on that account appears as a sharp point.
PP 1, which is formed by the lens, limits the aperture of the pencils of rays on the object-side; consequently it is the entrance pupil of the instrument.
In this case also the illumination must fall to zero by the vignetting of the pencils coming from objects at the margin of the field of view.
For lenses of short focus the diameter of the pupil is too large, and diaphragms must be employed which strongly diminish the aperture of the pencils, and so reduce the errors, but with a falling off of illumination.
Axial aberration is reduced by distributing the refraction between two lenses; and by placing the two lenses farther apart the errors of the pencils of rays proceeding from points lying outside the axis are reduced.
These anastigmatic lenses, which are manufactured up to X 40, are chromatically and spherically corrected, and for a middle diaphragm the errors of lateral pencils, distortion, astigmatism and coma are eliminated.
According to the laws of optics it is only possible either to portray a small object near one of the foci of the system with wide pencils, or to produce an image from a relatively large object by correspondingly narrow pencils.
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.
For the eyepiece the other rule holds; the object is represented by narrow pencils, and it is hence possible to subject the relatively great object, viz.
For strong objectives there is, however, only one optical tube length in which it is possible to obtain a good image by means of wide pencils, any alteration of the tube length involving a considerable spoiling of the image.
But as the object-side focus F2 lies behind the eyepiece, the real image is not produced, but the converging pencils from the objective are changed by the eyepiece into parallels; and the point 0 1 in the top of the object y appears at the top to the eye, i.e.
The position of the diaphragm limiting the pencils proceeding from the object-points is not constant in the compound microscope.
If the pencils are limited in the objective, the restriction of the pencil proceeding from the object-point is effected by either the front lens itself, by the boundary of a lens lying behind, by a real diaphragm placed between or behind the objective, or by a diaphragm-image.
This is specially important, for otherwise pencils from points placed somewhat laterally to the axis arrive with diminished aperture at the image.
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.
As the pencils used in the representations are of wide aperture on the object-side, only such points as are proportionately very near the focal plane can produce such small dispersion circles on the plane focused for, that they, so far as the objectiveand eyepiece-magnification permit, appear as points to the eye.
The pencils producing the real image are very much more acute, and their inclination is the smaller the stronger the magnification.
The eyepiece, which by means of narrow pencils represents the relatively large real image at infinity, transmits from all points of this real image parallel pencils, whereby the inclination of the principal rays becomes further increased.
13, we suppose that a diffracting particle of such fineness is placed at 0 that the diffracted pencils of the 1st order make an angle w with the axis; the principal maximum of the Fraunhofer diffraction phenomena lies in F' 1; and the two diffraction maxima of the 1st order in P' and P' 1.
Moreover, with such exceptionally narrow pencils shadows are formed on the retina of the observer's eye, from the irregularities in the eye itself.
These two conditions are only compatible when the representation is made with quite narrow pencils, and where the apertures are so small that the sines and tangents are of about the same value.
He also showed the influence of the cover-slip on pencils of such wide aperture.
The eye-lens converts diverging pencils into parallels.
He next gives by aid of these projective rows and pencils a new generation of conics and ruled quadric surfaces, "which leads quicker and more directly than former methods into the inner nature of conics and reveals to us the organic connexion of their innumerable properties and mysteries."
Thus, in the Crossley transmitter four hard carbon pencils were arranged in a lozenge-shaped figure, the ends of each pencil resting loosely in a small carbon block.
In the Ader transmitter as many as twelve carbon pencils were employed, arranged in a series of two groups with six pencils in parallel in each group. These were supported at their ends in parallel carbon bars, which were carried by a nearly horizontal wooden diaphragm.
There are large slaughtering establishments, and factories for the refining of sugar and for the manufacture of tobacco goods, soap and perfumery, lead pencils, iron and steel, railway cars, chemicals, rubber goods, silk goods, dressed lumber, and malt liquors.
The linear transformation replaces points on lines through the origin by corresponding points on projectively corresponding lines through the origin; it therefore replaces a pencil of lines by another pencil, which corresponds projectively, and harmonic and other properties of pencils which are unaltered by linear transformation we may expect to find indicated in the invariant system.
On a larger scale several pencils are used to make the connexions between carbon blocks which form the end walls of the furnace, while the side walls are of fire-brick laid upon one another without mortar.
Virginiana) are both much used in joinery and in the manufacture of pencils; though other woods are now superseding them for pencil-making.
The city has an extensive coal trade and numerous manufactures, among which are lead pencils, leather goods, silk goods, wall-paper and caskets.
The Cumberland graphite, which is especially suitable for pencils, contains about 12% of impurities.
It doesn't matter that the person selling pencils doesn't know how the pencil is made; he only needs to know how to sell them.
And it doesn't matter that the person who paints the pencils doesn't know how the paint is made, for his job is to paint them.
And yet pencils get made, more than a billion of them a year, and they are essentially given away.
She wandered back to the safety of her room, wanting paper and pencils, her favorite jeans … anything familiar to comfort her.