The gold chloride of commerce, which is used in photography, is really a hydrochloride, chlorauric or aurichloric acid, HAuC1 4.3H 2 O, and is obtained in long yellow needles by crystallizing the acid solution.
19th century, both the use and the improvement of reflectors were left mainly in British hands; but the gift of the " Crossley " instrument in 1895, to the Lick observatory, and its splendid subsequent performances in nebular photography, brought similar tools of research into extensive use among American astronomers; and they are now, for many of the various purposes of astrophysics, strongly preferred to refractors.
The limit can be depressed only by a diminution in Xo, such as photography makes possible, or by an increase in /2, the refractive index of the medium in which the object is situated.
In 1876 he successfully applied photography to the study of the ultra-violet region of stellar spectra.
The adoption, by Sir William Huggins in 1876, of gelatine or dry plates in celestial photography was a change of decisive import.
The aminophenols also find application as developers in photography, the more important of these developers being amidol, the hydrochloride of diaminophenol, ortol, the hydrochloride of para-methylaminophenol, C6H4.
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.
Originally the maps were engraved on copper, and the progress of publication was slow; but since the introduction of modern processes, such as electrotyping (in 1840), photography (in 1855) and zincography (in 1859), it has been rapid.
Before the application of photography, the camera lucida was of considerable importance to draughtsmen.
His chief title to fame, however, is his pioneering work in the application of the art of photography to astronomical research.
2nd Image Object Mirror Image without Lens camera obscura, which was extensively used in sketching from nature before the introduction of photography, although it is now scarcely to be seen except as an interesting side-show at places of popular resort.
In the last quarter of the 19th century spectroscopy and photography together worked a revolution in observational astronomy, and in both branches Huggins acted as pioneer.
The photography of prominences was, after some preliminary trials by C. A.
It has thus come about that astrophysics owes its recent development, and its recognition as a distinct branch of astronomical science, to the combination of the processes involved in the three arts of spectroscopy, photography and photometry.
He did much to advance stellar photography and its use in cataloguing the stars, and he was responsible for the geodetic surveys of Natal and Cape Colony, British Bechuanaland, German S.-W.
Uranyl nitrate is used in photography, and also in analytical chemistry as a precipitant for phosphoric acid (as uranyl ammonium phosphate, U02 NH4 P04).
The chloride,CdC1 2, bromide,CdBr 2, and iodide,Cdl2,arealsoknown, cadmium iodide being sometimes used in photography, as it is one of the few iodides which are soluble in alcohol.
Duchenne (Mecanisme de la physiognomie humaine, Paris, 1862) showed that by the use of electricity the action of the separate muscles could be studied and by the aid of photography accurately represented.
This artifice is specially adopted in objectives for astronomical photography ("pure actinic achromatism").
Before the development of photography, there was no possible way of making observations upon the heavenly bodies except by the eye.
In recent times photography has been so successfully applied to the mapping of our satellites as nearly to supersede visual observation.
The development of the method has been greatly assisted by photography, while the application of photometric measurements has been a powerful auxiliary in the work.
Although some lurking errors impaired the authority of the concluded parallaxes this work ranks as a valuable contribution to astronomy, since it showed the possibility of employing photography in such delicate investigations.
In a similar manner, for systems used in photography, the vertex of the colour curve must be placed in the position of the maximum sensibility of the plates; G'; and to accomplish this the F and violet mercury lines are united.
For ordinary photography, however, there is this disadvantage: the image on the focussing-screen and the correct adjustment of the photographic sensitive plate are not in register; in astronomical photography this difference is constant, but in other kinds it depends on the distance of the objects.
Daguerre for the invention of photography, the grant for the publication of the works of P. Fermat and Laplace, the acquisition of the museum of Cluny, the development of railways and electric telegraphs, the improvement of the navigation of the Seine, and the boring of the artesian wells at Grenelle.
The following branches have especially felt his influence: - chemical physics, capillarity and viscosity, theory of gases, flow of liquids, photography, optics, colour vision, wave theory, electric and magnetic problems, electrical measurements, elasticity, sound and hydrodynamics.
The great development of photography has been a notable aid to explorers, not only by placing at their disposal a faithful and ready means of recording the features of a country and the types of inhabitants, but by supplying a method of quick and accurate topographical surveying.
The advances in stellar photography made by Paul and Prosper Henry and others suggested to him the magnificent idea of obtaining, through the collaboration of astronomers in all parts of the world, an autographic picture of the entire sphere containing more than fifty million stars, which should faithfully record in future ages the state of the sky at the end of the i 9th century.
The camera obscura was first applied to photography (q.v.) probably about 1794, by Thomas Wedgwood.
By the use of photography, however, it is possible to photograph the trail of a star as it transits the meridian when the telescope is directed towards the north, and another trail be similarly photographed when the telescope is directed towards the south.