5 So 



POPULAR SCIENCE MONTHLY. 



which a plate (marked D) was joined, carrying the magnifying glass. 

 The latter is indicated in the circle above the letter D, near the tail- 

 fin of the fish. The eye Mas applied close to this circular magnifying- 

 glass, which was brought into position and adjusted by means of screws. 

 The two small sketches show a front and a back view of another one 

 of his microscopes. The small circle shows the position of the lens 

 inserted in a metallic plate. On the opposite side was a sort of object 

 holder, whose position was controlled by screws. In some instances, he 

 had a concave reflector with a hole in the center, in which his magni- 



fy ik: 





"t 



./ : a 





r ; m.i 



Fig. 



Leeuwknhukk's Microscope. 



Fig v Capillary Circulation, after 

 Leeuwenhoek. 



lying-glass was inserted, and, in this form of the instrument, the ob- 

 jects were illuminated by reflected and not by transmitted light. 



His microscopic observations were described and sent to learned 

 societies in the form of letters. "All or nearly all that he did in a 

 literary way was after the manner of an epistle," and these were so 

 numerous as to justify the cognomen, 'The man of many letters.' "'Tin' 

 French Academy of Sciences, of which he was elected a corresponding 

 member in 169?', got twenty-seven; hut the lion's share fell to the 

 young Royal Society of London, which in fifty years — 1673-1723 — re- 



