120 THE HISTORY AND DEVELOPMENT OF THE MICROSCOPE 



prolialile (lint bv no means certain) that Hans and Zacharias Janssen, 

 spectacle makers, of Middellmrg, Holland, were the inventors. But 

 it \\ould appear that the earliest microscope was constructed for 

 observing olijects bv rellected light only. 



At the Loan Collection of Scientific Instruments in London in 

 |s7fian old microscope, which had been found at Middellmrg, was 

 >hown. which. Professor Harting considered, might possibly have 

 been made by the -lansseiis. It is drawn ill fig. 90, and consists of 

 a combination of a convex object-lens and a convex eye- 

 lens, \\hich form was not published as an actual con- 

 struction until 1646 by Fontana, which, as Mr. Mayall 

 points out, does not harmonise with the assumption 

 that this instrument was constructed by one of the 

 Janssens. 



It is strictly a compound microscope, and the dis- 

 tance between the lenses can be regulated by two 

 draw-tubes. There are three diaphragms, and the eye- 

 lens lies in a wood cell, and is held there by a wire ring 

 sprung in. The object-lens, a, is loose in the actual 

 instrument, but was originally fixed in a similar way 

 to b. 



It cannot be an easy task if it be even a pos- 

 sible one to definitely determine upon the actual indi- 

 vidual 01- individuals by whom the compound micro- 

 scope was first invented. Recently some valuable 

 evidence has been adduced claiming its sole invention 

 for Galileo. In a memoir published in 1888 1 Professor 

 G. Govi, who has made the ijiiestion a subject of large and continuous 

 research, certainly adduces c\ ideiice of a kind not "easily waived. 



Huygheiis and, following him, many others assign the invention 

 of the compound microscope to Cornelius Drebbel, a Dutchman, in 

 the year 1621 ; but it has been suggested that he derived his know- 

 ledge from Zacharias .lanssen or his father, Hans Janssen, spectacle 

 makers, in Holland about the year 1590; while Fontana, a Nea- 

 politan, claimed the discovery for himself in 1618. It is said that 

 the Janssens presented the liVst microscope to Charles Albert, Arch 

 duke of Austria; and Sir I). Brewster states, in his 'Treatise' on the 

 Microscope,' that one of their microscopes which they presented to 

 Prince Maurice was in 1(517 in the possession of Cornelius Drebbel, 

 then mathematician to the Court of .lames I., where 'he made 

 microscopes and passed them oil' as his own invention.' 



we are told by Yiviani. an Italian mathematician, 

 ife of Galileo,' that -this great man was led to the discovery 

 the microscope from that of the telescope/ and that 'in 1612 he 

 senl one fco Sigismund, King of I'oland.' 



At ' "" u receive evidence through the researches of Govi that 

 invention was solely due to Galileo in the year 1(510. Professor 



FIG. ltd. 



' Janssen's ' 



compound 





. 



simple microscope' an instrument 'consisting 

 ''"- or mirror,' and l.y 'compound microscope' one 'con- 



il. ii. series ii. II microscopic composto 



V.s. !'i. IV. iss'.l. p. .-71. 



