INTRODUCTION OF THE MICROSCOPE 81 
he began to use the microscope is not known; his first pub- 
lication in reference to microscopic objects did not appear 
till 1673, when he was forty-one years old. 
His Microscopes.—He gave good descriptions and draw- 
ings of his instruments, and those still in existence have been 
described by Carpenter and others, and in consequence we 
have a very good idea of his working equipment. During 
his, lifetime he sent as a present to the Royal Society of 
London twenty-six microscopes, each provided with an object 
to examine. Unfortunately, these were removed from the 
rooms of the society and lost during the eighteenth century. 
His lenses were of fine quality and were ground by himself. 
They were nearly all simple lenses, of small size but con- 
siderable curvature, and needed to be brought close to the 
object examined. He had different microscopes for different 
purposes, giving a range of magnifying powers from 40 to 270 
diameters and possibly higher. The number of his lenses is 
surprising; he possessed not less than 247 complete micro- 
scopes, two of which were provided with double lenses, and 
one with a triplet. In addition to the above, he had 172 
lenses set between plates of metal, which give a total of 419 
lenses used by him in his observations. Three were of 
quartz, or rock crystal; the rest were of glass. More than 
one-half the lenses were mounted in silver; three were in 
gold. 
It is to be understood that all his microscopes were of 
simple construction; no tubes, no mirror; simple pieces 
of metal to hold the magnifying-glass and the objects to 
be examined, with screws to adjust the position and the 
focus. 
The three aspects of one of eeuwenhoek’s microscopes 
shown in Fig. 1g will give a very good idea of how they were 
constructed. These pictures represent the actual size of 
the instrument. The photographs were made by Professor 
6 
