1881.] 



MICEOSCOPICAL JOUENAL. 



235 



six years his skill and ingenuity largely 

 contributed to the reputation of the house. 

 In 1840 he commenced business on his 

 own account, devoting himself particularly 

 to the microscope and the specialties re- 

 quired in ophthalmic surgery. In 1842 

 he contributed a paper to the Academic 

 des Sciences (Tome xiv), describing the 

 construction of achromatic lenses, in 

 which curves of half a millimetre in radius 

 were utilized. From that date he received 

 encouragement from some of the leading 

 scientific men of Europe, such as Amici, 

 Arago, Milne-Edwards,and later on of Drs, 

 Lebert, Robin, etc., for whom he executed 

 numberless experimental devices. In 1843 

 he exhibited at the Academic des Scien- 

 ces his camera lucida, which is still re- 

 garded as one of the best forms of that 

 instrument. In 1844-5-6, his name ap- 

 pears in the Comptes-Rendus with numer- 

 ous improvements of the microscope. In 

 1847 he brought out his prism for oblique 

 illumination, using the mirror in the axis 

 — the forerunner of a large number of 

 devices in which the total internal reflec- 

 tion of glass surfaces has been utilized. 

 His son then joined him in partnership, 

 and the firm brought out in rapid succes- 

 sion binocular microscopes, dissecting mi- 

 croscopes, etc., which occupy a prominent 

 place in the popular text-books. M. Na- 

 chet's liberality in carrying out the cons- 

 truction of experimental apparatus ren- 

 dered his house a favorite resort of 

 amateurs of the microscope. For some 

 years past he had ceased to take part in 

 the business. His death took place in 

 Paris on the 28th ult., in his 83d year. " 



Prof. John Bacon. — We have also 

 to record the death of Prof. John Ba- 

 con, at his home, in Boston, on Mon- 

 day, Nov. 28th. Prof. Bacon was 

 one of the earliest American micro- 

 scopists. For nearly forty years he 

 has seen the progress of microscopi- 

 cal study and the improvements in 

 the instrument, securing for himself 

 whatever seemed to be of value among 

 the latter. About the year 1847 he 

 visited Andrew Ross, in London, who 

 then informed him that 147" was the 

 utmost limit of angular aperture that 

 could be given to an objective. 



For fourteen years he was Profes- 

 sor of chemistry in Harvard College, 

 but in 1 87 1 he resigned on account 



of ill health ; since then he has given 

 special attention to the study of dia- 

 toms. His cabinet of diatom-prepara- 

 tions is very valuable, and his library 

 contains perhaps the most complete 

 collection of works on the diatoms in 

 the country. He was a man of ability 

 and an excellent chemist, but of a re- 

 tiring disposition, and therefore almost 

 unknown to the general public. 



o 



Eye-pieces. — A committe of the 

 American Society of Microsopists, 

 appointed at the Detroit meeting, but 

 continued this year with the addition 

 of Dr. Blackham, has issued a circu- 

 lar especially addressed to manufac- 

 turers of microscopes, the object of 

 which is to secure uniformity in the 

 nomenclature and in the size of ocu- 

 lars. If the Society can accomplish 

 this very desirable end it need ask 

 for no greater fame. Is the task a 

 hopeless one ? We would like to know 

 what replies have been received up to 

 this time — how many manufacturers 

 heartily sympathize with the move- 

 ment, commend it in highest terms, 

 but, for various reasons, answer " No" 

 to the fourth question, which reads : 

 " Will you adopt such a nomenclature 

 if decided upon by this Society ;" or 

 to the tenth question, " Will you adopt 

 a standard set of sizes, if agreed upon 

 and recommended by this Society ? " 

 We would like to believe that all 

 American and English manufacturers 

 would feel themselves bound by the 

 interests of their customers, to adopt 

 such a set of standards — and in our 

 opinion not more than two sizes of 

 tube should be adopted, a small tube 

 and a large tube. But we can see 

 why large manufacturers may object to 

 changing their sizes, because of the 

 expense involved, and we believe that 

 the only way to secure this uniformity 

 is to present its advantages so clearly 

 before the purchasers of microscopes 

 that they will demand it. Neverthe- 

 less, we believe the efforts of the 

 committee will be productive of some 

 good. If proper judgment is exer- 

 cised in selecting the standard, 



