128 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE 



microscope, by Giuseppe Campani, which was published first in 1686, 

 which is presented in fig. 93 ; its close similarity to * Galileo micro- 

 scopes ' is plainly apparent, making it still more improbable that 

 these could be given a date prior to 1642. 



In a journal of the travels of M. de Monconys, published in 

 1665, there is a description of his microscope which is of much 

 interest. He states that the distance from the object to the first 

 lens is one inch and a half ; the focus of the first lens is one inch ; 

 the distance from the first lens to the second is fifteen 

 inches ; the focus of the second lens, one inch and a half; 

 distance from the second to the third, one inch and 

 eight lines ; the focus of the third lens, one inch and 

 eight lines ; and the distance from the eye to the third 

 lens, eight lines. 



This would form the data of a pr.ictic.il com- 

 pound microscope with a field lens ; and as Mon- 

 conys had this instrument made in 1660 by the 

 ' son-in-law of Yiselius,' it becomes probable in a 

 very high degree that to him must be attributed 

 the earliest device of a microscope with a field- 

 lens. 



In 1665 Hooke published his ' Micro- 

 graphia,' giving an account and a figure of 

 his compound microscope. He adopted 

 the field-lens employed by Monconys and 

 gives details as to the mode and object 



FIG. 94. Hooke's compound microscope (1665). 



