68 



ELEMENTARY PHOTO-MICROGRAPHY. 



Such sketches in microscopical societies may 

 be advantageously made on white cards of uniform 

 size, 5x4, when they serve a two-fold purpose. 

 First, that of encouraging members to make 

 careful and accurate observations, and, again, of 

 recording the work done by the society. Members, 

 too, will find the subsequent identification and 

 classification of species greatly accentuate their 

 interest. 



FIG. 23. 



The front of card is shown in fig. 24, with 

 sketch, or preferably a photograph, pasted on, and 

 the back of card in fig. 25. 



Power of objective and eyepiece, mode of illumi- 

 nation, brand of plate, and exposure may be added 

 where necessary. 



The cards should then be inserted in an album 

 from which they can be readily withdrawn, and 

 the album put in circulation for any definite period. 

 After return from its round, the album is refilled 

 with fresh cards, whilst the old ones are put in 



