and Laboratory Methods. 



1785 



Fig. 3). We have obtained the best results in this and in strictly photomicro- 

 graphic work by using a Thompson 9U° arc lamp. With this lamp the glowing 

 carbon is in the optical axis of the lantern so that the source of light is perma- 

 nently centered. The hand feed lamp is much to be preferred to the automatic 

 form. The lamp is supported on an adjustable stand so that it may be raised 

 or lowered and tilted at any desired angle. The image of the glowing carbon is 

 projected directly upon the object to be photographed. 



The apparatus in this form has 

 proved very useful for photographing 

 such objects as cannot be readily 

 placed in a vertical position before the 

 horizontal camera. Preparations or 

 dissections, fish, etc., may be photo- 

 graphed thus under liquid (Fig. 7). 



To use the camera with the mi- 

 croscope it is necessary to attach the 

 microscope to a leveling plate. This 

 is a cast iron plate* 17 x '2b cm. and 

 6 mm. thick. It is strengthened by 

 two transverse ribs each 2.5 cm. wide 

 and 6 mm. thick, which extend across 

 its lower surface at a distance of 3 cm. 

 from the ends. At its corners are 

 truncated rectangular pyramidal feet 8 

 mm. high and these are pierced by 

 leveling screws. Ear-like projections 

 extend from either end and through 

 them pass iron binding screws, by 

 means of which the plate may be 

 screwed to small iron plates set into 

 the floor. The upper surface of the 

 leveling plate is provided with stops 

 against which the base of the mi- 

 croscope fits, with felt pads for the mi- 

 croscope to rest on and with a binding 

 screw, by means of which a metal strio 

 is clamped across the base of the microscope to hold it to the plate (Fig. 4). 



To the end of the plate back of the microscope is attached a socket from 

 which rises an iron rod 12 mm. in diameter. The rod is vertically adjustable by 

 a thumb screw in the socket. At the top of this rod is a cross bar for bearing a 

 pair of pulley wheels which may be set at any point on the backwardly project- 

 ing limb of the cross bar. To one end of the axis of the pulley is attached by 



Fig. 3. 



-The apparatus in use with the 

 microscope. 



*The parts of the apparatus not regularly supplied by Zeiss were made by the University 

 mechanician, Mr. Ralph Miller, Ann Arbor, Michigan. He is prepared to furnish duplicate 

 parts as follows : camera stand top and supports, base plates, leveling plate for microscope, 

 focusing gear for microscope, shutter, metal pan with adjustable bottom. 



