124 An account of the Electro- Magnetic Engine. 



had the weight on board, which was large, been properly distributed 

 throughout the boat, which drew 2\ feet of water. The machine, 

 when on board, occupied a space \1\ feet in breadth, and 2| in 

 length. 



The battery consisted of 320 pairs of plates, arranged along the sides 

 of the boat, leaving sufficient room for twelve persons. The whole 

 battery could be brought into play only for a short time, in conse- 

 quence of a trifling fault in the connexion, which it was impossible 

 to correct on the spot. The consumption of zinc, or rather the pro- 

 duction of vitriol of zinc, per horse power, could not be exactly ascer- 

 tained ; but it would appear from the experiments, that this could not 

 be very considerable, inasmuch as the original weight of the zinc 

 being 400 pounds, and presenting a surface of 96 square feet, had de- 

 creased but 24 pounds in weight, during from two to three months that 

 the experiments were continued. 



Provided the health of Professor Jacobi allow him, he intends con- 

 structing an electro-magnetic machine of 40 to 50-horse power, and to 

 adapt it to the propulsion of a vessel. 



We must also mention Cyprian Callet's (of New York) electro-mag- 

 netic machine. (Patent Uth July, 1838.) On a balance, similar to 

 that of a steam-engine, connecting rods are attached at both sides, 

 which are again connected with strong iron bars, shaped like the 

 shoulders of a Brahmah pump. These bars are firmly encircled by 

 electro-magnetic spiral coils. From another point of the balancer a 

 connecting rod passed to the crank in the horizontal axle of a fly- 

 wheel ; and commutation wheels, on Jacobi's principle, are attached to 

 the same, in order to transfer the electric currents from the battery to 

 the spirals. As soon as an electric current is conveyed by means of 

 one of the spirals, the bar, which is already in a measure encircled, is 

 driven with considerable force into the spiral, and a power is thereby 

 engendered, which, from the fly-wheel, may be applied to the propul- 

 sion of boats, vehicles, machinery, &c. 



According to a written communication from Forbes, addressed to 

 Faraday, dated October 7th, 1839, it would seem that R. Davidson has 

 for the last two years had a small waggon and a lathe propelled by an 

 electro-magnetic machine. The galvanic battery for the foregoing con- 

 sists of a square foot of zinc surface, and the lathe is of sufficient power 

 to turn small articles, Davidson is said to be the first who attempted 

 to produce motion, not by reversing the poles, but by a momentary 

 suspension of the magnetic virtue. 



Davenport, who has constructed the most powerful machines pro- 



