ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 971 



largely to the reputation of that house for improvements in the manu- 

 facture of Microscopes. In 1840 M. Nachet commenced business as 

 an optician on his own account, confining himself principally to the 

 Microscope, and specialities required by surgeon-oculists. In 1842 he 

 contributed a paper to the Academic des Sciences (tome xiv.) de- 

 scribing the construction of achromatic objectives in which curvatures 

 of 0*5 mm. radius were employed. From that date he received the 

 advice and encouragement of some of the leading scientific men of the 

 Continent : Amici, Arago, Babinet, Eegnault, Milne-Edwards, and later 

 Drs. Lebert and Charles Eobin entrusted him with the execution of 

 numberless experimental devices. In 1843 he again appeared before 

 the Academic des Sciences (vide tome xvii.) with improved high- 

 power objectives, and his camera lucida for vertical Microscopes. In 

 1844 (loc. cit. tome xviii.) he exhibited a Microscope composed of a 

 doublet with a concave ocular (since developed into the " Loupe de 

 Briicke "). In 1845 {loc. cit. tome xx.) he produced improved high 

 powers using a fourth achromatic combination. In 1846 (loc. cit. 

 tome xxii.) he devised his erecting Microscope for dissecting, &c., 

 which was described in Quekett's work. In 1847 (loc. cit. tome 

 xxiv.) he brought out his well-known prism for oblique illumination 

 to be used in combination with the mirror in the optic axis. At 

 that date his son Alfred was admitted into partnership, and various 

 forms of binoculars, &c., have since been devised by the firm, which 

 are referred to in the popular text-books of the Microscope. For 

 some years past M. Nachet, Sen., had taken no active part in the 

 business. Those who knew him personally will remember his kindli- 

 ness, and also the liberality with which he carried out the construction 

 of experimental apparatus. His lifetime may be said to comprise the 

 whole period of the development of the compound achromatic Micro- 

 scope from the earliest doublets up to the latest homogeneous-immer- 

 sion objectives. 



We have also to record the death of a well-known eminent 

 American optician Mr. Charles A. Spencer, which took place on Sep- 

 tember 28th at Geneva, N.Y., in his sixty-eighth year. Mr. Spencer 

 commenced work as an optician immediately on finishing his studies at 

 Hobart College. Upwards of thirty years ago he produced dry objec- 

 tives having apertures of 170° and higher, one of which was specially 

 commended by Dr. Eobinson, of Dublin. Mr. Spencer's objectives 

 were much appreciated by the principal microscopists in America, such 

 as Professors Bailey, Henry, Bache, Pierce, H. L. Smith, and Drs. 

 Woodward and Torrey . President Barnard, of Columbia College, N.T., 

 was mainly instrumental in inducing Mr, Spencer to send specimens 

 of his objectives to the Paris Exhibition of 1878, where a gold medal 

 was awarded for their excellence. Mr, Spencer leaves two sons who 

 have been associated with him for some years in the production of 

 microscope objectives. He was one of the earliest to produce immer- 

 sion objectives having apertures exceeding the maximum of dry 

 objectives of 180°. 



