and Laboratory Methods. 1783 



adjusting the clamps on the frame the length of the camera bellows may be 

 varied. The frame slides back and forth in four grooved supports which are 

 screwed to the top of an iron stand. This top is a heavy I-shaped casting 

 bolted to the rest of the stand. 



In order to use the camera in a vertical position a duplicate was made of the 

 top of the camera stand and of the grooved supports. This was bolted to a 

 rectangular cast iron base plate 18 x SO cm. and 2 cm. thick. The plate had 

 three holes along each side for ^-inch lag screws. By means of these it was 

 attached to a two-inch pine board a little larger than itself and previously screwed 

 to the brick wall. The lower edge of the base is 90 cm. from the floor, upon 

 which the microscope is to stand.* (See Fig. 1.) 



The camera when placed in the new vertical supports (see below) must be 

 counterpoised. A hole is bored through the cross bar at one end of the frame 

 and into this a brass ring is inserted. To the ring is attached a snaffle from 

 which a heavy window cord runs through an ordinary iron pulley attached to the 

 ceiling directly over the camera, and then through a second pulley placed in any 

 convenient position on the ceiling. The end of the rope carries the counter- 

 poise, equal in weight to the entire camera. If the upper section of the camera 

 has been removed so that the lower alone may be used, then the counterpoise 

 should be lessened by an amount equal to the upper section or else a weight 

 equal to the weight of the upper section should be attached to the lower camera 

 section. 



In order to remove the camera from the horizontal supports the screws hold- 

 ing the supports of one side to the top of the camera stand should be loosened 

 so as to permit the supports to tip outward. The side of the frame against these 

 loosened supports should then be lifted so that the frame rotates on the opposite 

 rod as an axis. Twisting or springing of the frame should be avoided. To 

 place the camera in the vertical supports it should be set on end on the floor 

 near them and the counterpoise rope snapped into place. It is convenient to 

 have a short rope attached to the snaffle by which it may be pulled down for 

 attachment to the camera (Fig. 1). The attached camera is then brought into 

 position opposite the supports. The supports of one side should have been pre- 

 viously loosened. One side of the frame is now placed against the unloosened 

 supports and the frame rotated on this side as an axis until the opposite side 

 comes into place against its own supports. The screws of the loosened supports 

 should then be tightened. 



As thus arranged the camera may be used with an ordinary photographic 

 lens attached (Fig. 2). As the sliding frame is provided with a centimeter scale, 

 the camera may be set at the length necessary to give the desired magnification. 

 It is convenient to construct a table of magnifications corresponding to different 

 camera lengths. Such a table for the Zeiss Anastigmatic Objective F. 1:72, 



*In the illustrations there is seen above the floor a platform supported on I bedms, which 

 are cemented into openings 40 cm. deep cut in the brick wall. Each I beam has holes drilled 

 in its upper flange and through these 2x4 scantling are screwed to the I beams. Upon the 

 scantling is laid a platform of 2-inch planking. The platform is thus independent of the floors 

 and does not feel the ordinary vibration of the building. All delicate photographic work is 

 done upon this platform. 



