ELEMENTARY PHOTO-MICROGRAPHY. 



2 3 



The advantage of a short tube is seen in the 

 much larger field when using low powers. If the 

 microscope have a polariscope attachment, all the 

 better, but this is not essential. It should have two 

 eyepieces, A and C, and a battery of good objec- 

 tives, say, to begin with, 3in., 2in., iin., ^in., to 

 which may be added afterwards */in. and i-i2in. 

 oil immersion, as the reader feels his way to use 

 higher powers. All these should be kept free from 

 dust and carefully cleaned with wash leather before 

 use. Cleanliness throughout is of the highest im- 

 portance. A mere dust over with a pocket handker- 

 chief is not sufficient. The mounted object to be 

 photographed should also be rubbed back and 

 front, for it is astonishing how readily dust and 

 hairs adhere, and it must be examined with the 

 focussing glass before one can be satisfied that it 

 is clean. 



Fig, 6. 



Fig. 7- 



Fig 8. 



Caution when touching the oil lamp not to grease 

 the fingers is advisable. A short black velvet tube to 

 fit over the eyepiece will be required to connect the 

 microscope with the opening in the quarter-plate 



