120 JOURNAL OF THE [April, 



of microscopical objects, taken by the late Prof. John W. 

 Draper, in 1853 or 1854, by means of a Heliostat of this same 

 model. 



Mr. George P. Scott, of Brooklyn, being present as a visitor, 

 on request, explained the peculiar points of his microscope and 

 its case, as announced in the programme. This microscope 

 possesses many ingenious appliances connected with the body, 

 the stage, and the sub-stage of the instrument. Especially 

 noticeable among these are the contrivances by which, with a 

 quarter revolution, the polarizer, the selenite, and the analyzer 

 of the polarizing apparatus can instantly be brought into use, or 

 turned to one side, so as to avoid all interference with the ex- 

 amination of an object by ordinary light. 



Mr. W. Wales gave the Society interesting information con- 

 cerning the difficulties encountered in the construction of 

 apochromatic objectives. 



A discussion followed upon the construction of sub-stages, 

 with especial reference to the necessity of a centring arrange- 

 ment for the Abbe condenser. 



Mr. C. S. Shultz exhibited nine slides, beautifully prepared, 

 and donated to the Cabinet of the Society, through him, by 

 Miss Mary A. Booth, of Longmeadow, Mass., as announced in 

 the programme. 



On resolution the thanks of the Society were tendered Miss 

 Booth for this gift. 



Mr, G. S. Woolman presented, for distribution among the 

 members, diatomaceous material from marine soundings, taken 

 at the depth of 1,000 fathoms in the Gulf Stream, off the coast 

 of New England. 



Mr. A. M. Cunningham, of Mobile, Ala., through the Corres- 

 ponding Secretary, donated, for distribution among the mem- 

 bers, diatomaceous material, employed as a " Silver-polish," 

 containing many perfect and elegant diatoms. On resolution 

 the thanks of the Society were tendered Mr. Cunningham for 

 this donation. 



According to a request, previously made by the President, 

 that this should be especially an "Apparatus-evening," many 

 interesting and valuable pieces of apparatus were exhibited, as 

 appears in the programme. 



