550 



Transactions of the Society. 



this certainly is an objection, but hardly so serious as personal 

 drawing. 



Briefly then, the method is to bring the object just to the 

 point of invisibility by reducing the W.A.* and then the 

 correction for antipoint will be the measure of the object. 

 Example : The flagellum of a certain micro-organism just dis- 

 appears with a W. A. of * 6, a screen being used ; an inspection 

 of the following antipoint correction table f shows that the correc- 

 tion for that W.A. is • 00,000,618 inch, or • 157 fi; this,,therefore, 

 must be the thickness of the flagellum. 



* See this Journal, 1901, p. 242. t Op. cit., 1904, p. 271. 



X Number of waves in an inch. 



