16 



NOTES AND QUERIES. 



[No. 192. 



more convenient, as immediately on being added 

 it decomposes some of the chloride of silver, and 

 forms iodide of silver. I am happy to find that 

 Mr. Pollock confirms me in the use of this salt, 

 •which I had long thought to improve the tone of 

 iny pictures. The liquid, which will become ra- 

 pidly very dark coloured, must be set aside in an 

 -open vessel in a warm place for some weeks, e.g. 

 till, when a positive is placed in it, left for a short 

 time, and then washed with water, it shows clean 

 and not mottled in the light. The solution may 

 be kept always exposed, and much improves by 

 this : if much used, it should be replenished with 

 a simple solution of hypo, three ounces or two 

 ounces to the pint ; if little used, it may be filled 

 up as much as evaporates with pure water. 



The positive is left in this solution till the re- 

 quired tint is obtained, when it is to be placed in 

 plain hypo, two ounces to the pint, and in about 

 a quarter of an hour transferred to a basin of pure 

 water, and well washed in several waters. The 

 other detail of Mr. Pollock's process is so ad- 

 mirably and clearly given, and so like that I 

 pursue, that I will not trouble your columns with 

 it again. 



The after-bath of pure hypo, is not absolutely 

 necessary ; and where it is desired to obtain fine 

 olive, and dark sepia, and black tints, a better 

 tone results from washing well, long, and fre- 

 quently, with water alone. 



This bath also gives very rich tints with paper, 

 prepared without albumen : viz. — 



Chloride of ammonium - - 5 grs. 



AVater - - - - 1 oz. 



Lay the paper on this, and then hang it up to dry, 

 and excite with ammonio-nitrate containing seventy 

 grains of nitrate of silver to one ounce of water. 

 Should the above solution not give the requisite 

 tints soon after being made, add more chloride of 

 silver ; but bear in mind that the solution will 

 then soon become saturated when setting posi- 

 tives, and when this occurs it must be rectified 

 by the addition of a small portion of fresh hypo, 

 alone. F. Maxwell Lyte. 



P. S. — I may add that I have only lately tried 

 the addition of the iodide of potassium to my 

 setting liquid, and so must qualify my recom- 

 mendation of it by saying so. 



Florian, Torquay. 



Stereoscopic Angles. — I am obliged to Messrs. 

 Shadbolt and Wilkinson for the information 

 given in reply to my Queries (Vol. vii., p. 505.). 

 My mode of operation is precisely that of Mb. 

 Wilkinson : " I obtain all the information I can 

 from every source; then try, and judge for myself." 

 Hence the present letter. 



I regret to be obliged to differ from Mr. Shad- 

 bolt, but there is a point in his communication 



which appears to me to arise from a misconception 

 of the stereoscopic problem. He says (p. 557.), 

 " for distant views there is in nature scarcely any 

 stereoscopic effect." Now, surely visual distance 

 is merely visual stereosity ; for, to see an object 

 solid is merely to see its parts in relief, some of 

 them appearing to project or recede from the 

 others. It is the difiiculty of producing this effect 

 in landscapes, by the ordinary camera process, that 

 renders views taken by such means so deficient in 

 air, or, as the artists term it, aerial perspective, 

 most distant objects seeming almost as near as 

 those in the foreground. This indeed is the main 

 defect of all photographs : they are true repre- 

 sentations of nature to one eye — cyclopean pic- 

 tures, as it were — appearing perfectly stereoscopic 

 with one eye closed, but seeming absolutely flat- 

 tened when viewed by the two eyes. I remem- 

 ber being shown a huge photograph of the city of 

 Berlin, taken from an eminence; and a more 

 violent caricature of nature I never set eyes upon. 

 It was almost Chinese in its perspective : the 

 house-tops appeared to have been mangled. It 

 was a wonderful work of art, photographically con- 

 sidered ; but artistically it was positively hideous. 

 But the same defect exists in all monophotogra- 

 phic representations, though in a less degree, and 

 consequently less apparent than in viewa to which 

 a sense of distance is essential. In portraits, the 

 features appear slightly flattened ; and until photo- 

 graphers are able to overcome this, the chief of all 

 obstacles to perfection, it is idle to talk of the art 

 giving a correct rendering of nature. This is what 

 is wanted, more than colour, diactinic lenses, mul- 

 tiplication of impressions, or anything else. And 

 when it is remembered that the law of an ordinary 

 convex lens is, the farther the object from the lens 

 the nearer the focus, and, vice versa., the nearer 

 the object the farther the focus, it becomes evident 

 that by such an instrument distant objects must 

 be made to appear near, and near objects distant, 

 and nature consequently mangled. 



The stereoscope gives us the only demonstrably 

 correct representation of nature ; and when that 

 instrument is rendered more simple, and the 

 peep-show character of the apparatus discon- 

 nected from it, the art of photography will tran- 

 scend the productions of the painter — but not 

 till then. 



I am anxious to obtain all the information I 

 can from such of your photographic readers as are 

 practically acquainted with the stereoscopic portion 

 of the art relative to the angles under which they 

 find it best to take their pictures for given dis- 

 tances. 



Mr. Fenton, the secretarjr of the Photographic 

 Society, takes his stereoscopic pictures, when the 

 objects are 50 feet and upwards from the camera, 

 at 1 in 25, This is, as Mr. Shadbolt states, Pro- 

 fessor Wheatstone's rule for distances. 



