98 ELECTRIC LIGHTING. 



J. Bellot, the maker of these machines, furnishes us with 

 the following particulars : 



"I have made two small bobbins one a Gramme, the 

 other with projections on Trouve's plan. Each has 20 coils. 

 The Gramme bobbin contains a greater length of wire by 20 

 per cent. These bobbins are so mounted as to be acted 

 upon by the same electro-magnet, which is wound with a 

 thick wire of a length proportional to the Gramme bobbin. 

 This last is perfectly insulated ; there is no loss between the 

 coils ; but it happens to be otherwise with the former, where 

 some of the coils are in communication with the iron. 



" In spite of these disadvantages I obtain a much better 

 result with the coil having projecting pieces. 



" The core of the coil, with projections, is made of four 

 sheets of iron, cut and riveted together so as to form a single 

 mass, which was finished on the lathe. This core is wound 

 with 75 metres of wire of 0-65 millimetre diameter. With 

 a velocity of rotation of 1,500 turns per minute I obtain a 

 current equal to that of 8 to 10 Bunsen cells. There is no 

 heating, even when no resistance is interposed in the ex- 

 ternal circuit." 



Lontin's Machine. Lontin's machine has a special in- 

 terest for us on account of the complementary machine by 

 which the effect is divided, and which is the first machine of 

 the kind ever invented. As we shall discuss this kind of 

 machine in a separate chapter, we shall here have but a few 

 words to say about the generator properly so called, which is 

 represented in Fig. 32. It consists of a core or iron drum, on 

 which are fixed a large number of iron cores in four rows 

 placed obliquely. These cores are furnished with magnetizing 

 coils, D D D, wound for tension in such a manner that the end 

 of one coil corresponds with the beginning of the next. This 

 system, called by its inventor a magnetic pinion, is mounted 

 on an axle so as to turn between the poles of a powerful 

 electro-magnet with flattened branches, A A, constituting the 



