204 PHOTO-MICROGRAPHY [CH. VIII 



| 272. To meet all the difficulties the object may be left in a horizontal 

 position and the camera made vertical (Fig. 161). 



Since 1879 such a camera has been in use in the Anatomical Department 

 of Cornell University for photographing all kinds of specimens; among these, 

 fresh brains and hardened brains have been photographed without the slightest 

 injury to them. Furthermore, as many specimens are so delicate that they 

 will not support their own weight, they may be photographed under alcohol 

 or water with a vertical camera and the result will be satisfactory as a photo- 

 graph and harmless to the specimen. 



A great field is also open for obtaining life-like portraits of water animals. 

 Freshly killed or etherized animals are put into a vessel of water with a con- 

 trasting back-ground and arranged as desired, then photographed. Fins have 

 something of their natural appearance and gills of branchiate salamanders 

 float out in the water in a natural way. In case the fish tends to float in the 

 water a little mercury injected into the abdomen or intestine will serve as 

 ballast. 



The photographs obtainable in water are almost if not quite as sharp as 

 those made in air. Even the corrugations on the scales of such fishes as the 

 sucker (Catostomus teres) show with great clearness. Indeed so good are the 

 results that excellent half tone plates may be produced from the pictuers thus 

 made, also excellent photogravures. In those cases, as in anatomical prepara- 

 tions, where a photograph rarely answers the requirements of a scientific figure, 

 still it serves as a most admirable basis for such a figure. The photograph is 

 made of the desired size and all the parts are in correct proportion and in the 

 correct relative position. From this photographic picture may be traced all 

 the outlines upon the drawing paper, and the artist can devote his whole time 

 and energy to giving the proper expression without the tedious labor of mak- 

 ing measurements. 



"While the use of photography for outlines as bases for figures diminishes 

 the labor of artists about one-half it increases that of the preparator; and herein 

 lies one of its chief merits. The photographs being exact images of the prep- 

 arations, the tendency will be to make them with greater care and delicacy, 

 and the result will be less imagination and more reality in published scientific 

 figures; and the objects prepared with such care will be preserved for future 

 reference." 



" In the use of photography for figures several considerations arise: (i) 

 The avoidance of distortion; (2) The adjustment of the camera to obtain an 

 image of the desired size; (3) Focusing; (4) Lighting and centering the object. 



(i). While the camera delineates rapidly, the image is liable to distortion. 

 I believe opticians are agreed, that, in order to obtain correct photographic 

 images, the objective must be properly made, and the plane of the object 

 must be parallel to the plane of the ground glass. Furthermore, as most of 

 the objects in natural history have not plane surfaces, but are situated in 

 several planes at different levels, the whole object may be made distinct by 

 using in the objective a diaphragm with a small opening. 



$273. Scale of Sizes and Focusing. (2). By placing the camera on a 

 long table and a scale of some kind against the wall, the exact position of the 



