NATURAL PHILOSOPHY. 179 



cipitation of metallic gold, and the formation of a chloride of silver. The 

 cause of the non-durability of photographs is suggested as due to the use of 

 the hydro-sulphate of soda; and ammonia has been suggested as better for 

 use, instead of the former. 



This phenomenon has also attracted attention during the past year in En- 

 gland ; and hi London a committee of scientific photographists has been con- 

 stituted, and a fund raised for inquiring into and reporting on the subject. 



The number of applications of the photographic art to the practical opera- 

 tions of every-day life, is rapidly increasing. An extensive coach-building 

 establishment in England has recently adopted the practice of having a photo- 

 graphic picture taken of every carriage finished. A picture in accurate 

 perspective is thus obtained, with every detail fully wrought out, in a manner 

 that would defy the highest powers of the best skilled artists. The customers, 

 also, of the establishment, who generally can make nothing out of plain, geo- 

 metrical side elevations and working drawings, are enabled to judge of the 

 actual effect of an equipage, before committing themselves to an order for it. 

 The camera also greatly assists the private operations of the coach-builder, 

 for, after finishing any complicated or uncommon kind of carriage, he can in 

 this way obtain a perfect representation of it, in aU its parts and proportions ; 

 so that he can build an exactly similar one at any subsequent time perhaps 

 after the lapse of many years, when the details might otherwise have been 

 forgotten. 



It is also obvious that this plan might with the same advantage be applied 

 to many other forms of construction as well as carriages. 



The introduction of photographic views as evidence in the case of suits and 

 trials at law, for the purpose of explaining the position of buildings, utensils, 

 nuisances, locations, etc., has been extensively resorted to in England. 



Photography has been used successfully at Paris hi taking views of clouds ; 

 they have been obtained by Bertsch in hardly a quarter of a second, in a style 

 that leaves nothing to be desired. These pictures are adapted to resolve all 

 important questions relative to their form, distribution, and height. M. 

 Pouillet measures the height by means of two photographic apparatuses 

 placed at a distance from one another. 



Another interesting use which has been made of the photographic art, has 

 been the delineation and reproduction of the scenes and localities of the 

 Crimean war. The London Athenaeum in noticing the wonderful accuracy 

 and life-like appearance of a published portfolio of these pictures, thus re- 

 marks : "For the first time since men fought we shall have history illustrated 

 by the certainty of a reporter who never blunders, never errs. Men will fall 

 before the battle-scythe of war, but not before this infallible sketcher has 

 caught their lineaments and given them an anonymous immortality more 

 lasting, perhaps, than 'storied urn or animated bust.' As photographists 

 grow stronger in nerve and cooler of head, we shall have not merely the 

 bivouac and the foraging party, but the battle itself painted ; and while the 

 Tate of nations is in the balance we shall hear of the chemist measuring out 

 his acids and rubbing his glasses to a polish. "We shah 1 then have indisput- 

 able tests for promotion ; and may, perhaps, form galleries of national victories 



