317 



AN IMPROVED COMPOUND MICROSCOPE BY JAMES 



MANN. 



By Edward M. Nelson, F.R.M.S. 

 {Read Oetoher 2Wi, 1911.) 



This microscope, which supplies three steps in the evolution of 

 the modern microscope, was kindly brought to my notice by 

 Mr. T. Court. 



The instrument is figured on a plate in a pamphlet * (dated 

 1751) which accompanies it. The microscope in the main is 

 obviously a copy of J. Cuff's (1744),t the improvements con- 

 sisting in the mirror and its attachment, and in making the 

 instrument portable. 



The first portable compound microscope was made by 

 CJeorge Adams in 1746, and in this instrument we see 

 Mann's device for adapting Adams's idea of portability to 

 Cuff's microscope. Very probably this was the second portable 

 compound microscope. 



There are, however, other and more important improvements : 

 (1) The mirror is plane and concave, thus predating that of 



* Title : *' A Description o the Compound (formerly called the Reflect- 

 ing or Double) Microscope, with great improvements. London made and 

 sold by James Mann, at the sign of Sir Isaac Newton's Head, and Two Pair 

 of Golden Spectacles, near the west end of St. Paul's, 1751." 



t Journ. Q. M. C, Ser. 2, Vol. VII., p. 116, fig. 23 (189S). 



