530 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



No. 20 iron wire .04 of an inch in diameter and three inches Ions' 

 was made red hot, but when the current from the magneto-electric 

 machine was sent throuofh the coils of electro-magnetic machine 

 the electricity from the latter melted eight inches of the same 

 sized wire and a length of twentj'-fonir inches was made red hot. 

 When the electro-magnet of a five inch machine was excited by 

 the two and a half inch magneto-electric machine, the electricity 

 from the former melted fifteen inches of No. 15 wire .075 of an 

 inch in diameter. 



Mr. Wilde then constructed a ten inch electro-raairnetic machine: 

 the electro-magnet weighs about three tons, and the weight of the 

 whole machine is about four and a half tons. It has two arma- 

 tures, one for producing "intensity'' and the other "quantity'^ 

 effects. The intensity armature is coiled with an insulated con- 

 ductor consisting of a bundle of thirteen No. 11 copper wire^ each 

 0.125 of an inch in diameter. The coil is 376 feet in length and 

 weighs 232 lbs. The quantity armature is enveloped with the 

 folds of a copper plate conductor (insulated), sixty-seven feet long 

 and weiijhing 344 lbs. 



These armatures are driven at a uniform velocity of 1,500 revo- 

 lutions a minute by means of a wide leather belt of the strongest 

 description. When the direct current from the one and five- 

 eighth inch magneto-electric machine, having on it six permanent 

 magnets, was transmitted through the five inch electro-magnetic 

 machine, and the current from the latter was sent through the ten 

 inch electro-magnet, an amount of magnetic force was developed 

 in the large magnet far exceeding anything heretofore produced, 

 accompanied by an evolution of d^auimic electricity from the 

 quantity armature so enormous as to melt iron wire .15 of an inch 

 in diameter and fifteen inches in lergth. The same arrangement 

 melted fifteen inches of copper wire 0.125 of an inch in diameter. 

 When the intensity armature was used the electricity melted seven 

 feet of wire 0.065 of an inch in diameter, and made led hot twenty- 

 one feet of the same kind of wire, but the illuminating power from 

 this armature is the most brilliant description. When an electric 

 lamp was used having gas-carbon pencils one-half an in^h square, 

 and placed on the top of a high building, the light evolved was 

 sufficient to cast shadows from the flames of street lamps a half a 

 mile distant. Sensitized photographic paper exposed to this light, 

 at a distance of twenty-five feet, for only twenty seconds, was dark- 



