The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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When dissolved add the following mixture after  it has become cold -
Sulphuric acid ... ...... ...        2 ozs.
Water ...............       10 ,,
When the paper is dried it is exposed under a negative or drawing for about 7 minutes, and then exposed to the vapour from a heated mixture of 1 part of aniline and 50 parts of water. The image then appears brown, and the print is left in a room full of steam for two hours, or till the image turns black, and finally washed in 1 : 6 ammonia water. (For other processes in which coal-tar colours are used, see Anthotype, Diazotype, and Feer's Process.)
Animals, Photographing. One of the first to make a special feature of photographing animals was Mr. F. York, and he used (about 1878) a double camera fitted with twin portrait lenses, both lenses racking out together. One lens made a guiding image on its own focussing screen, while the other lens pro-jected a similar image on the sensitive plate. This double camera- was called a "Zoological Camera," and such a device rendered it easy to focus and adjust accurately - indeed, to follow a moving animal, fine focus-
sing all the time, and to make the exposure at any instant. In other words, we have here a camera with a full - size focussing finder; an excellent system when zoological work is to be done.
More recent forms of York's Zoological Camera. The above-mentioned system of the full-size focussing finder is not completely satisfactory unless the finder lens is of the same excellence as the actual photographic lens. Mr. York's lead
in the matter of the zoological
Fig. 4.
camera has been very much fol-lowed by later workers; thus, Bolas's hand camera of 1881 was a twin-lens camera, one lens for focussing and the other for actual photographic work, and quite early in the days of the commercial