MECHANICS AND USEFUL ARTS. 45 



diameters are reduced one half, etc. In other words, having a 

 machine of a certain power, and a certain degree of heat is re- 

 quired, the diameters of the obstructing media may be reduced or 

 increased in order to accommodate them to the power of the 

 machine. 



In order to warm an American oaf upon this phxn, allowing for 

 a tray placed in the floor of the car, in front of each seat, it is 

 estimated it would require an entire length of the chain or coil of 

 about 360 feet, and in which the obstructing media form an asrsi'e- 

 gate length of about 70 feet ; so that to accomplish this it would 

 require a machine to heat this latter number of feet of small wire. 



Although this may be a new application of electricity, and no 

 machines can now be obtained already organized, and of sufficient 

 power to be applied for this purpose, English electricians have 

 made estimates of machines which come within all the require- 

 ments, as to power, space occupied, weight,- power to operate 

 them, etc., to make the invention practical and economical. Even 

 with machines constructed for light-house purposes, 18 feet of 

 number 20 iron wire can be melted instantly ; and the fact is well 

 known to electricians, if the same machine were organized for 

 producing a current of quantity, the heating power would be 

 greatly increased. 



The inventor is not aware of any chemical battery by means 

 of which this invention may be economically applied. In this 

 case, the law of equivalents is in the way ; and there must be a 

 destruction of the battery corresponding to the amount of heat 

 produced. In the course of time, however, chemical batteries 

 may be constructed so as to be applied advantageously, as, for in- 

 stance, those having large metallic surfaces exposed to a weak 

 chemical action ; or earth currents may be accumulated and util- 

 ized for this purpose ; but for the present he relies entirel}'^ upon 

 the magneto-electric machine. Advantage may be taken of a 

 train of cars going down grade, when usually the steam is cut off 

 and the brakes put down, without taxing the locomotive at all ; 

 whereas, in case of combustion of coal, the loss is the same 

 whether going up or down grade. Among some of the advan- 

 taofes claimed for this method of heating railroad cars are the 

 following : — 



First, its economy ; second, its safety ; and third, its comfort. 

 Concerning its economy, the trays may be constructed of hard 

 wood, and covered by any metal, but copper would be best, on 

 account of its absorbing heat more rapidly and retaining it longer. 

 As regards the cost of magnet machines, this would be materially 

 reduced if they were made by machinery and in large numbers, 

 instead of by hand. There would be but little wear and tear of 

 them except at certain points ; and in case the magnets should in 

 time become weakened, they could be easily taken apart and re- 

 charged. There being no strain or wear and tear upon the coil, 

 being protected from injury by the plate covering it, and, besides, 

 there being no possibility of its becoming oxidized by the degree 

 of heat it would be subjected to, — say 120 or 140 degrees, — it is 

 supposed it would last for an indefinite period. It is to be borno 



