CHAP, vii.] MAGNETO- ELECTRIC MACHINES. 663 



"brought them to a high degree of power. Fig. 434 represents one of 

 these apparatus as at work in the lighthouse of Heve, on the coast of 

 La Manche. 



A very solidly-made framework of iron carries several series of 

 eight horse-shoe magnets ranged as radii of as many circumferences 

 as there a,re bobbins, opposite to whose armatures of soft iron their 

 poles are placed. The eight pairs of bobbins of each series of magnets 

 are supported on bronze wheels, and the ends of their wires are 

 attached to wooden discs or plates fixed to the wheels. A single axis 

 of rotation turns on fixed sockets in the framework and carries with 

 it all the discs and bobbins, whose armatures thus pass rapidly before 

 the poles of the magnets. An indefinite series of induced currents 

 results, which by the arrangements adopted are all in the same 

 direction, and together form what may 

 be called a continual source of electricity. 

 By collecting this electricity by means 

 of two wires running to the carbonholders 

 of an electric lamp, a .light of considerable 

 intensity is obtained. 



The first suggestion of a magneto- 

 electric machine capable of giving a con- 

 tinuous current always in the^same direction 

 is due to Dr. A. Pacinotti, of Florence, F]G 43;1 _ Course of tbe curreut in 

 whose essential feature was a novel form 



of armature to which lie gave the name of " transversal electro-magnet." 

 This armature was formed of a toothed iron ring, m m (Fig. 431), capable 

 of rotating on a vertical axis, M M, and having the spaces between the 

 teeth occupied by helices of copper wire covered with silk. The wire 

 of the helices was always wound in the same direction round the ring, 

 and the terminal end of each helix was brought into metallic connec- 

 tion with the adjoining end of the wire of the succeeding helix. From 

 these junctions connecting wires were carried down parallel to the 

 axis of the machine, and united to insulated plates of brass, of which a 

 double row, as shown in the figure, were inserted in a wooden cylinder, 

 c, which was itself firmly attached to the lower part of the axis. The 

 current entered through the successive brass plates as they came into 

 contact with a small metallic roller, Jc, which was in communication 

 with one pole of a voltaic battery. At the point of junction with the 



