110 Mr. Wilde — Researches in Magnetism and Electricity . [Apr. 26, 



equal velocity of 2500 revolutions per minute. When the electricity from 

 the magneto-electric machine was transmitted through a piece of No. 20 

 iron wire 0*04 of an inch in diameter, a length of 3 inches of this wire was 

 made red-hot. When the direct current from the magneto-electric machine 

 was transmitted through the coils of the electro-magnet of the electro- 

 magnetic machine, the electricity from the latter melted 8 inches of the 

 same-sized iron wire as was used in the preceding experiment, and a length 

 of 24 inches was made red-hot. 



When the electro-magnet of a 5-inch machine was excited by the 2-i-inch 

 magneto-electric machine, the electricity from the 5-inch electro-magnetic 

 machine melted 15 inches of No. 15 iron wire 0"075 of an inch in diameter. 



The author having found that an increase in the dimensions of the 

 machines was accompanied by a proportionate and satisfactory increase of 

 the magnetic and electric forces, a 10-inch electro-magnetic machine was 

 constructed : the weight of its electro-magnet is nearly 3 tons, and the 

 total weight of the machine is about A\ tons. The machine is furnished 

 with two armatures — one for the production of intensity"-, and the other 

 for the production of " quantity" -effects. 



The intensity armature is coiled with an insulated conductor consisting 

 of a bundle of thirteen No. 11 copper wires, each 0*125 of an inch in dia- 

 meter. The coil is 3/6 feet in length, and weighs 232 lbs. 



The quantity armature is enveloped with the folds of an insulated copper- 

 plate conductor 67 feet in length, the weight of which is 344 lbs. These 

 armatures are driven at a uniform velocity of 1500 revolutions per minute, 

 by means of a broad leather belt of the strongest description. 



When the direct current from the l|^-inch magneto-electric machine, 

 having on its cylinder six permanent magnets, was transmitted through 

 the coils of the electro-magnet of the 5-inch electro-magnetic machine, 

 and when the direct current from the latter was simultaneously, and in like 

 manner, transmitted through the coils of the electro-magnet of the J 0-inch 

 machine, an amount of magnetic force was developed in the large electro- 

 magnet far exceeding anything which has hitherto been produced, accom- 

 panied by the evolution of an amount of dynamic electricity from the 

 quantity armature so enormous as to melt pieces of cylindrical iron rod 

 15 inches in length, and fully one-quarter of an inch in diameter. With 

 the same arrangement, the electricity from the quantity armature also 

 melted 15 inches of No. 11 copper wire 0*125 of an inch in diameter. 



When the intensity armature was placed in the magnet cylinder, the 

 electricity from it melted 7 feet of No. 16 iron wire 0*065 of an inch in 

 diameter, and made a length of 21 feet of the same wire red-hot. 



The illuminating power of the electricity from the intensity armature is, 

 as might be expected, of the most splendid description. When an electric 

 lamp, furnished with rods of gas- carbon half an inch square, was placed at 

 the top of a lofty building, the light evolved from it w^as sufficient to cast 

 the shadows from the flames of the street-lamps a quarter of a mile distant 



