69 



The finding of a break in the cable is similar in some 

 respects, he said, to the process just described. 



The lecturer then explained by diagrams the duplex or 

 double transmission system, where two messages are sent 

 at the same time in opposite directions upon the same 

 wire without interference. 



The lecture was closed by a series of brilliant experi- 

 ments in electro-magnetism, the electric light, the defla- 

 gration of metals by the electric current, and the explosion 

 of electric torpedoes. 



REGULAR MEETING, MONDAY, APRIL 5, 1875. 



MEETING this evening at 7.30 o'clock. The PRESIDENT 

 in the chair. Eecords of preceding meeting read. 



The SECRETARY announced the following correspon- 

 dence : 



From George H.Allen, Boston, March 2,22; Samuel L. Boardman, Augusta, 

 Me., March 17 ; John M. Bradbury, Ipawich, March 1; Waldo Higginson, Boston, 

 March 2; Frank M. Caryl, Franklin, N. J., March 22; A. P. Mayer, Hoboken, N. J., 

 March 1; George B. Gavett, Boston, March 10; Rufus King, New York, March 24; 

 C. F. Maynard, Newton ville, March 5; Thomas E. Proctor, Boston, March 4; R. 

 Ridgway, Washington, D. C., March 21, 29; Smith & Co., Woburn, April 1; Bristol 

 Naturalist Society, Feb. 28; Liverpool Literary and Philosophical .Society, Jan. ; 

 Rhode Island Historical Society, March 9; Buffalo Historical Society, March 24; 

 Jowa State Historical Society, March 30; Maryland Historical Society, March 26; 

 New York Historical Society, March 26; Wein, K. Akademie der Wissenschaften, 

 Mun 9, 16; Worcester, Public Library, March 24. 



The LIBRARIAN reported the following additions to the 

 library : 



By Donation. 



KELLEY, JAMES H. Essex Register for 1828, 1829. 1 vol. folio. 

 MACKENZIE, 8. S., of Topsfleld. Miscellaneous pamphlets, 15. 

 MASS. HORTICULTURAL SOCIETY. Transactions of. 1874, pt 11. 

 MERCANTILE LIBRAKT ASSOCIATION OF SAN FRANCISCO. Twenty-Second 

 Annual Report. 1874. 



