US TJIK IllsTuKV AXI) DEVELOPMENT OF THE MIGEOSCOPE 



micron-ope, by (iinseppe Campani, which was published first in 1686, 

 \\hich is presented in fig. 93 ; its close similarity to 'Galileo micro- 

 scopes' is plainly apparent, making- it still move improbable that 

 these cmilil !> given a date prior to 1642. 



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

 I iiii."). there is a description of his microscope which is of much 

 interest. He .Mates 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 

 'i-ht lines; the focus of the third lens, one inch and 

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

 lens, eight lilies. 



This would form the data of a practical com- 

 pound microscope with a field lens ; and as Mon- 

 conys had this instrument made in 1660 by the 

 'son in lau of Viselius,' it becomes probable in a 

 very ///<//> </t*i/ree that to him must be attributed 

 the earliest device of a microscope, with a field- 

 lens. 



In 16(55 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 



94 -Hooke's '. 



miiTi>M-i>i>r i lf.C.."ii. 



