174 Louis Schwendler — On the Employment of, Sfc. [No. 3i 



while in No. X, for a total circuit resistance o£ 65-29, the sent current is 

 onlj 7'14!. The error of observation is therefore obvious. 



That vrith such strong received currents as are produced when the 

 dynamo-electric machine is used, the lines should work well, is not to be 

 wondered at. But it was also confirmed by the outstations having to 

 adjust their relays much more unsensitively. 



Supposing now that we had useful work day and niglit for the strong 

 main current, and that on the whole the new method could be always 

 depended upon, I believe these experiments have proved that the signal- 

 ling currents required in telegraph stations could be had for nothing, and 

 that the method would be quite practicable. 



The useful work for the main current at night would most conveniently 

 take the shape of an electric light to illuminate very efficiently the Signal 

 Office. The electric light, besides being more powerful, would possess the 

 additional advantage of being produced by at least 50 times less heat 

 than if the same light were obtained by combustion. This is no doubt a 

 great advantage in a hot climate. During the daytime, I would use the main 

 current for jDuUing punkhas, lifting messages, or, more generally, for work- 

 ing a pneumatic system of sending and receiving messages, &c., &c. If 

 Calcutta had the good fortune to possess a colder climate, it might he 

 suggested that the heat developed in the coil of wire should be used for 

 warming rooms. It would then only be necessary to lead the wire along 

 the walls, in a manner similar to that in which hot water pipes often are 

 for heating rooms ; the electric method being only far more economical. 

 The heat given up by the wire, after dynamic equilibrium of the system has 

 been established, is quite regular, and the method is obviously exceedingly 

 clean and very convenient for domestic purposes. The wire attained 

 its constant temperature of 93° C. after the current had acted for about 

 half an hour, the air of the room having a temperature of 30° C. 



The heat given out by the wire is by no means small. For instance, 

 in our case, the average current working through a resistance r = 1'543 

 b. a. u. was 36801 milli-oersteds. This represents work done at a rate 

 of 20^73 Si ergs per second, and supposing the wire has obtained its 

 constant temperature, this whole energy is developed into heat emitted by 



204<73 



the wire into space at a rate of — = 488 gramme-degree-centigrade 



per second. This is equal to the heat produced by an ordinary German 

 stove consuming 6H)S of coals per hour ; supposing that the loss of heat 

 when coals are burnt under a steam-boiler is four times as great as when they 

 are burnt in a German stove. It appears, therefore, that the heat developed 

 by the wire would be sufficient to keep a moderately sized and ordinarily 

 ventilated room at a comfortable temperature even when situated in the 

 highest latitudes. 



