American Fisheries Society 251 



the combination of holes and paraffine it is possible to "lay 

 out" a specimen in a natural position on the glass, on the 

 work table, and to know that it will stay in place while an 

 exposure is made. 



The next step in the improvement of the glass screen was 

 the use of rubber sucking disks with wire pins attached, 

 such as are used by window trimmers and others. The 

 disks if moistened adhere to the glass with sufficient firmness 

 to admit the impaling of specimens of considerable size and 

 weight on the sharp wire points. The specimen is attached in 

 such a way as to hide the sucking disks from view. The 

 disks, while adhering firmly, at the same time admit of the 

 readjustment or rearrangement of the object to be photo- 

 graphed on the screen, which in many cases makes the disk 

 method to be preferred over the two methods of attachment 

 just described. 



The success met with by the use of the vertical glass 

 screen in photographing dry objects in the air naturally led 

 to the application of the apparatus and the principle involved 

 to the producing of shadowless pictures of various forms 

 of aquatic life. All that was necessary was to provide a 

 fair sized aquarium — under ordinary conditions the best 

 dimensions would be twenty inches high, twenty-four inches 

 long, and twelve inches between the back and front. The 

 two sides must be of good quality, very heavy plate glass. 

 The ordinary battery jar will not be satisfactory as it is 

 pressed into its form and as a result all the surfaces are 

 rough and irregular. The irregularities of the surface 

 cause curious refractions that give no end of trouble to the 

 photographer. For the ends and bottom of the aquarium 

 wood is to be preferred; it can be left its natural color or 

 painted white if desired. 



With the camera, aquarium, and background arranged 

 with reference to the light as shown (in slide), the operator 

 arranges his specimens, for example, three or four freshly- 

 caught fish, by impaling them on the pins of the sucking 

 disks, and carefully transfers the glass screen with the speci- 



