24 ELEMENTARY PHOTO-MICROGRAPHY. 



camera, the lens having been removed, as it is not 

 required when using the microscope. A small iris 

 diaphragm called a Davis shutter will be found 

 useful for getting better penetration and definition. 

 This screws into the body tube of the microscope at 

 one end, and receives the objective at the other 

 end. It removes any halo or glare, and enables 

 a sharp picture to be taken. For feathers, eggs of 

 insects, and polycystina it is almost indispensable. 



A carpenter may be got to construct a simple 

 baseboard, on which the lamp, microscope, and 

 camera may be placed. At one end of the board 

 two flanges are fastened, between which a block 

 bearing the camera on the top slides freely to and 

 from the microscope. This sliding block again has 

 flanges to receive the small camera and keep it 

 rigidly in position whilst drawing the dark slide. 

 Two thumbscrews in one flange of the baseboard 

 will fix the sliding block, and will secure both block 

 and camera after connection with the microscope 

 by means of a velvet tube has been made. 



Note that the bellows of the camera must be 

 capable of full extension when placed in the recess 

 on the top of the block. Thus any degree of en- 

 largement may be obtained by racking the bellows 

 in or out without disturbing the connections. A 

 reference to the sketch, fig. 8, will make this clear. 



Fig. 6 is a board about 5ft. long Sin. wide, and 

 lin. thick. Fig. 7 is the end view showing flanges, 

 say, 2in. deep. The sliding block, fig. 8, slides 

 freely between these flanges, and is fixed by the 



