316 PEOCEEDINGS OF THE AMERICAN ACADEMY 



Six hundred and eiglity-second Meeting. 



June 8, 1875. — Adjourned Annual Meeting. 



The President in the chair. 



The President announced the death of M. Charles de 

 Rerausat, Foreign Honorary Member. 



The Corresponding Secretary read a letter from M. Bar- 

 rande, acknowledging his election into the Academy. 



Voted, To adjonrn the meeting in August to the second 

 Tuesday in October. 



The following papers were presented : — 



" On tlie Hexatomic Compounds of Cobalt." By Dr. 

 Wolcctt Gibbs. 



" On the Supposed Perchloride of Manganese." By Pro- 

 fessor J. P. Cooke, Jr. 



" On the Use of Field Instruments in Astronomy." By 

 Professor T. H. Safford. 



" On Photographing Spectrum Lines." By Dr. Robert 

 Amory. 



" On a Comparison of Prismatic and Diffraction Spectra." 

 By Professor E. C. Pickering. 



" On a New Method of Calibration." By Professor E. C. 

 Pickering. 



" On a New Instrument for Projecting Lissajou's Curves." 

 By Professor E. C. Pickering. 



On the " Theory of Discount in the Game of Billiards." 

 By Professor Benjamin Peirce. 



Professor WiUiam Watson presented a set of models illus- 

 trating his " Descriptive Geometry." 



Six hundred and eighty-third Meeting. 



October 12, 1875. — Adjourned Stated Meeting. 



The Vice-President in the chair. 



The Vice-President announced the death of Professor 

 Joseph Winlock, and Mr. Chauncey Wright. 



