412 PROCEEDINGS OF THE AMERICAN ACADEMY 



Carl Friedrich Wilhelm Ludwig, of Leipsic, to be a Foreign 

 Honorary Member in Class II., Section 3, in place of the late 

 Theodor Schwann. 



The following papers were presented : — 



Comparisons of Photometric Observations on the Light of 

 the Stars, made by Sir William Herschel. By Edward C. 

 Pickering. 



On the Effect of Change of Temperature on Hall's Phe- 

 nomena. By Edwin H. Hall. (By invitation.) 



Contributions from the Physical Laboratory of Harvard 

 College : 



On the Thomson Effect. By John Trowbridge and C. B. 

 Penrose. 



Influence of Magnetism on Thermal Conductivity. By 

 John Trowbridge and C. B. Penrose. 



Electromotive Force. By John Trowbridge. 



Change of Pitch by the Telephone. By John Trowbridge. 



Seven bundred and fifty-sixth Meeting. 



November 8, 1882. — Monthly Meeting. 



The President in the chair. 



Li the absence of the Recording Secretary, Mr. Edmands 

 was ap[)ointed Secretary ^ro tern. 



The President read a letter from the Directors of the 

 Royal Society of Sciences of Gottingen, announcing the death 

 of their secretary, Friedrich Wohler ; also a letter from 

 Dr. Charles S. Minot, acknowledging his election as Fellow 

 of the Academy. 



The following paper was presented by title : — 



The Tortugas and Florida Reef. By Alexander Agassiz. 



Professor Dolbear made some remarks on the maximum 

 temperature of the sun. He also spoke of an attempt to 

 determine the relative amounts of electricity transmitted by 

 different parts of the cross section of a conductor. Re- 

 marks on this subject were made by Messrs Pickering and 

 Edmands. 



