Thus a monochromatic image of the sun is built up on the fixed photographic plate.
They all squeezed into the front seat—the back seat was piled high with photographic equipment and camping gear.
Photographic telescope was afterwards added, no fewer than 75,000 photographs had been obtained up to the beginning of 1901.
A ray of light is directed upon the mirror, and the motion of the latter, due to the varying strengths and direction of the received currents, is made to write the transmitted signals upon a strip of bromide photographic paper about three inches wide.
Potassium ferrous oxalate, FeK2(C204)2 H20, is a strong reducing agent and is used as a photographic developer.
The height of the walls in the various observatories, the height of the collectors, and the distance they project from the wall vary largely, and sometimes electrometer, and they sometimes leave hardly a trace on the photographic paper.
The application of photography to exact astronomy has created the necessity for new forms of apparatus to measure the relative positions of stellar and planetary images on photographic plates, and the relative positions of lines in photographic spectra.
It is practically impossible to work with the sensitive film in contact with the reseau-film, not only because dust particles and contact would injure the silver film, but also because the plate-glass used for the photographic plates is seldom a perfect plane.
The discrepancies produced in this way are, however, very small, if care is taken to minimize the distance between the silver film and the photographic plate and to select a reasonably good piece of glass for the reseau.
The object glass of the micrometer-microscope is placed midway between the plane of the photographic plate and the plane of the micrometer webs.
164) described a measuring-machine by Repsolds, in which the micrometermicroscope tilts in the bearings of the chariot on which it moves, so that it can view either a graduated scale or the photographic plate.
In the Korn apparatus the light from a Nernst electric lamp is concentrated to a point by means of a lens on the original picture, which is wound on a glass cylinder in the shape of a transparent photographic film.
At the receiving station a cylinder - which revolves synchronously with the transmitting cylinder - is covered with a photographic film or paper, upon a point of which a pencil of light from a Nernst lamp is concentrated.
Aperture evoked the comment in his journal for that year, "There is not now a single person employed or instrument used in the observatory which was there in Mr Pond's time"; and the transformation was completed by the inauguration of spectroscopic work in 1868 and of the photographic registration of sun-spots in 1873.
A much easier method, applicable to glass originals, is that of photographic reproduction by contact printing.
It is, in fact, admitted that some of the glasses, most useful optically, the dense barium crown glasses, which are so widely used in modern photographic lenses, cannot be produced entirely free either from noticeable colour or from numerous small bubbles, while the chemical nature of these glasses is so sensitive that considerable care is required to protect the surfaces of lenses made from them if serious tarnishing is to be avoided.
The increasing importance of the camera obscura as a photographic instrument makes it desirable to bring together what is known of its early history, which is far more extensive than is usually recognized.
The photographic method appears to have practically failed during recent years, since there has been no brilliant display upon which to test its capacity.
It contains numerous illustrations; maps of the routes of the ancient aqueducts and the city of Rome in the time of Frontinus; a photographic reproduction of the only MS. (the Monte Cassino); several explanatory chapters, and a concise bibliography, in which special reference is made to P. d Tissot, E tude sur la condition des agrimensores (1879).
Great skill is shown in this operation, which achieves perhaps the finest facsimile reproduction of drawings ever known withotit the aid of photographic processes.
Interesting stars are: a Aurigae or Capella (the goat), one of the brightest stars in the heavens, determined by Newall and Campbell to be a spectroscopic binary; [3 Aurigae, a star of the second magnitude also a spectroscopic binary; e Aurigae, an irregularly variable star; and Nova Aurigae, a "new" star discovered by Anderson in 1892, and afterwards found on a photographic plate exposed at Harvard in December 1891.
Many experiments have also been made by the use of photographic plates in order to find the greatest depth to which light penetrates.
Later apparatus, such as Pettersson's bifilar current-meter or his more recent electric-photographic apparatus, and Nansen and Ekman's propeller current-meter, measure both the direction and the velocity at any moderate depth from an anchored vessel.
His experiments, in the same year, on the photographic registration of stellar spectra, marked an innovation of a momentous character.
But the wet collodion process was then the only one available, and its inconveniences were such as to preclude its extensive employment; the real triumphs of photographic astronomy began in 1875 with Huggins's adoption and adaptation of the gelatine dry plate.
Rochester ranks first among the cities of the United States in the manufacture of photographic materials and apparatus and optical instruments.
His earliest work was concerned with improvements in photographic processes; and then, in association with J.
In 1854 he turned his attention to solar physics, and for the purpose of obtaining a daily photographic representation of the state of the solar surface he devised the photo-heliograph, described in his report to the British Association, "On Celestial Photography in England" (1859), and in his Bakerian Lecture (Phil.
A was published in photographic facsimile in 1879-1880.] Codex Ephraemi Syri Rescriptus (Paris Nat.
He especially devoted himself to investigations of the radiation of heat from the sun and its absorption by the earth's atmosphere, and to that end devised various delicate methods and instruments, including his electric compensation pyrheliometer, invented in 1893, and apparatus for obtaining a photographic representation of the infra-red spectrum (1895).
From 1847 to 1862 he was advising astronomer to the headquarters of the army and navy; chairman of the International Astronomical Congress from 1867-1878; acting president of the International Metric Commission in 1872; and president of the International Congress for a Photographic Survey of the Stars in 1887, in which year he was also made a privy councillor.
Had the copies made of ancient writings been mechanical reproductions of the originals, such as the photographic facsimiles of modern times, there would have been little here for textual criticism to do.
The telescope serves to examine the image of the slit and to measure the angular separation of the different slit images; when photographic methods are employed the telescope is replaced by a camera.
In importance next to visual observation, and in the opinion of some, surpassing it, is the photographic method.
Schumann 2 have shown, however, that with the help of spectroscopes void of air and specially prepared photographic plates, spectra can be registered as far down as lzoo A.
Photographic methods have been employed successfully by Sir W.
Balmer's formula received a striking confirmation when it was found to include the ultra-violet lines which were discovered by Sir William Huggins' in the photographic spectra of stars.
By suitably replacing the ocular of the observing telescope in an angular vision spectroscope by a photographic camera, it is possible to photograph spectra; such instruments are termed spectrographs.
Suppose a fixed image of the sun to be formed on the collimator slit of this spectroscope, and a photographic plate, with its plane parallel to the plane of the solar image, to be mounted almost in contact with the camera slit.
Beyond the camera slit, and almost in contact with*it, the photographic plate-carrier (j) is mounted on a fixed support.
The eyepiece is removed and the photographic plate (k) placed in position.
Characteristic, also, is their action on a photographic plate, and the phosphorescence which they occasion when they impinge on zinc sulphide and some other salts.
With this arrangement of crossed slits a spot of light impinges on the photographic surface and, when the boom is steady, gives a sharp fine line.
These experiences are like photographic negatives, until language develops them and brings out the memory-images.
The cutter employed to rule these lines removes the silver in fine lines from the surface of the glass, Thus, if a photographic plate, before it is exposed in the telescope, is placed with its sensitive surface nearly in contact with the silvered surface of this reseau, and if parallel light, normal to the surface of the plate, is allowed to fall on the silvered film through the glass on which the film has been deposited, that light will pass through the fine lines in the silver film where the silver has been removed by the cutter, but will otherwise be intercepted by the silver film.
In addition to these we have the photographic plates in F.
The salts of the acid, however, are stable, the sodium salt in particular being largely used for photographic purposes under the name of "hypo."
Photographic processes have been utilized not only in reducing maps to a smaller scale, but also for producing stones and plates from which they may be printed.
In the Rocky Mountains surveys photographic apparatus is successfully employed.
He was distinguished as the discoverer of radioactivity, having found in 1896 that uranium at ordinary temperatures emits an invisible radiation which in many respects resembles Rntgen rays, and can affect a photographic plate after passing through thin plates of metal.
The Germans laid the greatest stress on measures with the heliometer; the Americans, English, and French on the photographic method.
The photographic right ascensions gave the values 8.80" -}- 0.007" -}- 0.0027" (Hinks) and 8.80" + 0 .
It is often difficult to obtain quite accurate or even adequate reproductions of scenes and subjects, and, when this is done, it is obviously necessary to refrain from treating the work of the old artists and sculptors as equivalent to photographic representations.
Huntingdon examined by photographic methods the absorption spectra of a great number of organic compounds.
By setting the camera slit so as to admit to the photographic plate the light of the denser calcium vapour, which lies at low levels, or that of the rarer vapour at high levels, the phenomena of various superposed regions of the atmosphere can be recorded.
The movements of the apparatus, which when complete should consist of two similar pendulums in planes at right angles to each other, are recorded by means of a beam of light, which, after reflection from the mirror or mirrors, passes through a cylindrical lens and is focussed upon a moving surface of photographic paper.
Its labors embraced not only Egypt and Nubia (as far as Khartum) but also the Egyptian monuments in Sinai and Syria; its immense harvest of material is of the highest value, the new device of taking paper impressions or squeezes giving Lepsius a great advantage over his predecessors, similar to that which was later conferred by the photographic camera.
Farrand spent more than a week in the crater trying to get some good photographic views, and Orton has given a graphic description of his experiences in the same place.
Later followed the appearance of lights; quasi-human voices; musical sounds, produced, it is said, without instruments; the "materialization" or presence in material form of what seemed to be human hands and faces, and ultimately of complete figures, alleged to be not those of any person present, and sometimes claimed by witnesses as deceased relatives; "psychography," or "direct writing and drawing," asserted to be done without human intervention; "spirit-photography," or the appearance on photographic plates of human and other forms when no counterpart was visible before the camera to any but specially endowed seers; 3 unfastening of cords and bonds; elongation of the medium's body; handling of red-hot coals; and the apparent passage of solids through solids without disintegration.
The manuscript maps intended to be produced by photographic processes upon stone, zinc or aluminium, are drawn on a scale somewhat larger than the scale on which they are to be printed, thus eliminating all those imperfections which are inherent in a pen-drawing.
Advantage was taken of the occasion to make photographic measures for parallax at various points of the earth on a very large scale.
Refractor to enable it to take part in the International Photographic Survey of the Heavens.