190 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ed and the bars are removed. The alloy melts at 500 Fahr., 

 aud expands considerably on cooling. It improves on re- 

 casting, but is always very brittle. The bars are arranged 

 radially around a temporary brass cylinder, a thin slip of 

 mica being inserted between the iron and the alloy to pre- 

 vent contact except at the point of junction. Eight or ten 

 of these bars form a ring, and the several rings are placed 

 one above another, insulated from each other by a circle of 

 asbestus. The inner ends of the bars are heated by a Bun- 

 sen burner, the flame issuing in small jets in the annular 

 space between the burner and the bars. The consumption 

 of gas is said to be one cubic foot for each volt of tension 

 per hour. The electromotive force of this combination is 

 such that twenty elements are about equal to one Daniell 

 cell about one volt. The following table, given on the au- 

 thority of Latimer Clark, gives the constants of these batter- 

 ies as sold in London : 



When hot, the resistance of the batteries rises about 25 

 per cent. The smallest of the above piles costs about $15, 

 the largest about $150. A battery of 375 pairs the inter- 

 nal resistance of which was 4.5 ohms, and the electromotive 

 force 14.6 volts deposited 180 grains of copper per hour. 

 The electric light which they give is powerful and constant ; 

 but it requires a large number of elements. Telegraphia 

 Journal^ 1876. 



THE GRAMME LIGHT IN EAILROAD DEPOTS. 



Sartiaux has communicated to the French Academy the 

 results of his experiments on the practical use of the electric 



