PRACTICAL PHOTO-MICROGRAPHY 



CHAPTER I 



INTRODUCTORY 



As an instrument of research, either in its application to scientific 

 work, or in its varied uses where scientific methods have been 

 applied industrially, the microscope now holds a pre-eminent 

 position. It was early recognised that some means of recording 

 the varied appearances of microscopic images was desirable, 

 and for many years no method but that of hand- drawing was 

 known. With the advent of photography these conditions 

 were changed, and it was at once recognised that the combina- 

 tion of photography with the microscope had great possibilities, 

 and opened up a fresh field for work. 



Photo-micrography has become, therefore, an important 

 branch of microscopic work, but it still suffers from certain 

 disabilities. When a microscopist is observing an image 

 under the microscope, he can so focus any particular plane of 

 the object as to bring out the part he wants, and can in a 

 drawing delineate this part only, suppressing the portions of 

 the image not required or entirely ehminating any ill-defined 

 areas. In viewing an object each successive plane can be 

 focussed, and so a general idea of its structure in depth can be 

 obtained. 



The quality of penetration, or the power of showing more 

 than one optical plane at a time, is not evident in any first- 

 rate high-power objective : in fact, the greater its excellence, 

 the less the depth of focus which it possesses. The photographer 

 has difficulty in embodying these appearances in his picture, 



