OF ARTS AND SCIENCES: MAY 24, 1870. 223 



Committee on the Library. 



Francis Parkman, Charles Pickering, 



John Bacon. 



Committee to audit the Treasurer's Accounts. 

 Charles E. Ware, Theodore Lyman. 



Professor Joseph Winlock exhibited a photograph of the 

 sun taken with a lens of forty feet focus, and four inches 

 aperture. As it is difficult to place a tube of this length in 

 an inclined position, it is laid horizontally, and an image of the 

 sun is reflected into it by a plane mirror of unsilvered glass. 

 When this mirror was blackened on one side, it became heated 

 to such an extent as to shorten the focus of the lens nearly 

 three feet. The image obtained is about four inches in diame- 

 ter, and is free from the distortion produced by an eye-piece. 

 The exposure is instantaneous, and is effected by passing a 

 diaphragm with a slit in it between the lens and mirror. A 

 better effect is thus obtained than by the usual method of 

 placing it near the plate-holder. The lens, which was made by 

 Messrs. Clark and Sons, is not achromatic, as its slight curva- 

 ture rendered this unnecessary. It was corrected for spheri- 

 cal aberration by means of an artificial star, produced by a 

 soda flame, and a collimator, of an aperture somewhat greater 

 than that of the lens. 



The Corresponding Secretary presented the following an- 

 nual report of the Council : — 



Since the last report of the Council, the following gentlemen have 

 been elected members of the Academy : — 



William T. Brigham, of Boston, to be a Resident Fellow in Class II., 

 Section 1. 



Algernon Coolidge, of Boston, to be a Resident Fellow in Class II., 

 Section 1. 



Alfred P. Rockwell, of Boston, to be a Resident Fellow in Class I., 

 .Section 4. 



Alpheus Hyatt, of Salem, to be a Resident Fellow in Class II., Sec- 

 tion 3. 



