GENERAL NOTES 137 



amplification of all exposures in diameters 

 and recording same in his note-book. This 

 is a matter that is all too frequently neg- 

 lected. It is quite a common thing to find 

 an article or even a whole book illustrated 

 by drawings, or reproductions of photo-mi- 

 crographs bearing the legend " highly magni- 

 fied;" this and nothing more, save the name 

 of the subject. Whether it be amplified ten, 

 or a hundred, or a thousand diameters, is all 

 one in this slipshod method of announcing 

 that it is magnified at all. It conveys no idea 

 whatever to one unacquainted with the origi- 

 nal as to its actual size, or in comparison 

 with the pictured enlargement. If every one 

 making a photo - micrograph would at the 

 time carefully measure its amplification in 

 diameters and make entry of same in his 

 note-book, it would add greatly to the prac- 

 tical value of his work. And it is so readily 

 done, requiring so little time, such few and 

 simple tools, that there is no excuse for neg- 

 lecting it. A stage micrometer ruled in TOT 

 and oW of an inch (or the metric scale if 

 preferred); a pair of dividers and a scale 

 divided in tenths of an inch, or in milli- 

 meters, comprise all the necessary apparatus. 

 The methods of use are equally simple. They 



