NATURAL rniLOsoriiY. 175 



ner. In a half hour an ahnost absolute vacuum is produced in a 

 tube provided with 2 platinum wires, placed at a distance of 

 2 millimetres, or about .08 of an inch. When the requisite tension 

 is obtained, the tube is heated to redness by charcoal or Berthelot's 

 lamp ; when the vacuum is so complete that a spark will not pass, 

 the communication is closed between the tube and the machine. 

 The electric spark in such a tube will not pass from cue platinum 

 point to the other over the above small interval. 



TELEGRAPHIC FEATS. 



On February 1, 1868, the wires of the Western Union Telegraph 

 Company from San Francisco to Plaister Cove, Cape Breton, and 

 the wires of the New York, Newfoundland, and London Telegraph 

 Company from Plaister Cove to Heart's Content were connected, 

 and a brisk conversation commenced between these two continen- 

 tal extremes. Compliments were passed between San Francisco 

 and Valentia, Ireland, when the latter announced that a message 

 ■was just then being received from London direct. This was said 

 at 7.20 A. M., Valentia time, Feb. 1. At 7.21 A. M., Valentia 

 time, the London message was started from Valentia to San Fran- 

 cisco; passed through New York at 2.35 a. m.. New York time ; 

 was received in San Francisco at 11.21 p. m., San Francisco 

 time, Jan. 31, and was at once acknowledged, — the whole pro- 

 cess occupying 2 minutes' actual time, and the distance about 

 14,000 miles. Immediately after the transmission of the above 

 message, the operator at San Francisco sent an 80-word message 

 to Heart's Content in 3 minutes, which the operator at Heart's 

 Content repeated back in 2 minutes 50 seconds, — distance about 

 5,000 miles. — New York Journal of the Telegi'apli. 



On the wires of the Western Union Telegraph Company, 94 

 messages of 20 words each were transmitted from Washington to 

 Cape Breton by one wire in an hour. On the same day 33 mes- 

 sages were sent in as many minutes from Cape Breton to New 

 Orleans. 



TREATMENT OF TUMORS BY ELECTRICITY. 



From the well-known facts that a slight occasional current of 

 galvanism will develop a muscle, while the continuous use of the 

 same current will, by over-stimulation, cause it again to waste, it 

 occurred to Dr. M. H. Collis that the absorption of tumors might 

 be brought about by this agency. After trying various forms of 

 battery, he returned to the simple voltaic pile, composed of a 

 dozen or more couples of zinc and copper, lj| inches square, or of 

 small cjiinders or plates of wood covered with felt and wrapped 

 round with zinc and copper wire. These are excited by salt and 

 water, or by sulphuric acid in the proportion of 1 to 20 parts of 

 wat6>v. The batteries of wire coiled on wood are much the light- 

 est, and more convenient in proportion to their strength ; they 

 preserve their activity sufficiently, and do not wear out so soon as 



