69 



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

 respects, he said, to the process jnst 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 Avas closed by a series of brilliant experi- 

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

 kgration of metals by the electric current, and the explosion 

 of electric torpedoes. 



Eegular Meeting, Monday, April 5, 1875. 



Meeting this evening at 7.30 o'clock. The President 

 in the chair. Records 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, Ipswich, March 1; Waldo Higginson, Boston, 

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

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

 New York Historical Society, March 2(i; Wein, K. Akademie der Wisseaschaften, 

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



The Librarian reported the following additions to the 



library : — 



By Donation. 



Kelt-et, James H. Essex Register for 1828, 1829. 1 vol. folio. 

 Mackenzie, S. S., of Topsfleld. Miscellaneous pamphlets, 15. 

 Mass. Horticultural Society. Transactions of. 1874, pt il. 

 Mercantile Library Association of San Fbancisco. Twenty-Second 

 Annual Report. 1874. 



