ELEMENTARY PHOTO-MICROGRAPHY. 19 



Only so recently as 1891 I had occasion to 

 require some photo-micrographs of sand, but, to 

 my surprise, I was informed that in a city of 

 400,000 inhabitants only two or three persons out- 

 side the Medical School were competent to do 

 the work. 



There is no reason why the art should be con- 

 fined to the select few, for, after all, the mysteries 

 are not so great that they may not be lessened by 

 a few preliminary trials, one or two failures being 

 sufficient to indicate the direction in which an 

 alteration should be made. The apparatus need 

 not be at all costly in order to produce good 

 results, although for high-class scientific research 

 everything must necessarily be of the best. 



Consequently, for the purpose of this book, 

 a special room, with massive foundations, in 

 a special district free from the vibration of 

 passing vehicular traffic, monochromatic and 

 electric or limelight, the heliostat for sunlight, 

 expensive apochromatic lenses, or even specially- 

 corrected microscope objectives, will not be re- 

 quisitioned for carrying out any of the instructions 

 hereinafter given, but only such simple apparatus 

 as the ordinary photographer possesses, with the 

 addition of a microscope. Indeed, for low power 

 work, a camera, a paraffin lamp or lantern, and a 

 few home-made articles are all that are essential, 

 no microscope being required, as the operation is 

 one of simple enlargement. 



