140 THE H1STOKY AND DEVELOPMENT OF THE MICROSCOPE 



the eve being placed behind in tlie direction D at any point the 

 >iiiide lens or ii coin) ihiatii in might require. 



( 'ulpeper mid Scarlet's microscope requires a note, and is illus- 

 trated in tig. His. It was inappropriately designated a ' reflecting ' 

 inicroM-ope. but this arose merely from the fact that it was the first 

 Knuli-li model which employed an illuminating mirror. It was, 

 however, a dioptric, not a catoptric instrument, and is figured in 

 Dr. Smith's ' Opticks,' 1738. 



A Pocket Reflecting Microscope' was figured by Benjamin 

 M;irtin in his ' Micrographia Xova ' in 1742, having the interesting 

 feature of a micrometer eye-piece depending on a screw with a certain 

 number of threads to the inch, and by which accurate measurements 

 could be t;d<en. It was called a reflecting microscope because it had 

 a mirror lilted into its cylindrical base; but it was, in reality, a 

 compound refracting form, and appears to have a good claim to have 



been the original from whence the 

 modern ' drum ' microscopes were 

 taken. 



Wilson devised a simple 

 screw-liarrel ' microscope in 1702, 

 and Baker describes and figures 

 in 1742 the Wilson model 

 mounted on a scroll standard and 

 with a mirror mounted on the ba-e 

 in a line with the optic axis. Fig. 

 ID'.I reproduces the drawing of 

 Adams. 



But Martin originated a large 

 number of improvements both in 

 the optical arrangements and the 

 mechanism of the microscope, and 

 was an excellent maker. He ap- 

 plied rack -and- pinion focussing ad- 

 justments, to the compound micro- 

 scope he added inclining move- 

 ments to the pillar carrying the 

 stage and mirror, and he furnished 

 the stage with rectangular movements. 



>vas to this maker that the late Professor Quekett was 

 indebted for an earlj microscope, of which he evidently to the last 

 thought highly, and which was subsequently purchased by the Royal 

 Microscopical Society. A drau ing of t his instrument is given in lin. 

 and should be described in (^ueketfs own words. He says : 

 stands aboul two feet in height, and is supported on a tripod 

 the central part or .stem. \\. is of triangular figure, having 

 , upon which the stage, <), and frame, D, support- 

 mirror. !;. are capable of being moved up or down. The 

 ', is three inches in diameter; it is composed of 

 ner of which contains the eye-piece, and can be 

 l( .v rack and pinion, so as t(. increase or diminish 

 power. At the base of the triangular bar is a cradle 



Fin. 109. Wilson's simple microscope 

 on scroll *t, i IK I. ml fas made by 

 Adams, 1746). 



