IOWA ACADEMY OF SCIENCES. 41 



photographing small objects, such as pieces of apparatus, 

 and botanical, zoological, and geological specimens. 



The table proper is 7 feet long by 24 inches wide, and 27 

 inches high, and is mounted on substantial two-wheeled 

 casters. The framework consists of two pieces, S, Fig. 1, 1 

 by 5 inches, and 7 feet long, for the sides; four cross 

 pieces, Q, 2 by 5 by 17 inches; and the four legs L, 2 by 3 

 inches, bolted on near the ends of S, and spreading some- 

 what so as to give greater stability. The top consists of 

 two thin boards of such width as to leave an opening or 

 slot, three-quarters of an inch wide, in the middle and run- 

 ning the whole length of the table. On the outside of the 

 side pieces are two rails, R, one (on the left) being flat, the 

 other having a ridge above. Upon these rails slide the 

 movable parts to be described. The ridged rail at the right 

 serves as a guide. The other rail, being flat, allows the 

 sliding parts to adjust themselves without binding, from 

 unequal expansion of the parts. 



The cross pieces of the frame are partly cut away under 

 the central slot, as shown at E, so as to allow the clamps 

 attached to the movable parts to move freely in the slot. 



The stand or pillar, on which the camera K is mounted 

 is fastened to the base U, which can slide sidewise between 

 guides at the front and back as a sub- base V, about 20 by 

 23 inches. It lies on the cleats W, which rest on the rails 

 R, upon which the whole may slide along the table. The 

 pillar may be firmly clamped to the table by tightening 

 the nut C, which raises the clamping screw that passes 

 through a transverse slot in U, a hole in V and the open- 

 ing in the table top. The screw is attached, below, to the 

 clamp which consists of a piece of wood about 6 inches 

 long and having the cross section shown above E. 



The pillar itself is adjustable in height. It consists of 

 two parts. The inner part I, being raised or lowered by 

 the large screw D, which passes through the nut N attached 

 to the movable portion I, I. To promote rigidity in this 

 structure it is made triangular in section, and when 

 adjusted to the proper height it may be clamped firmly by 

 the three-way clamping device shown in cross section 



4 I AS 



