DYNAMO-ELECTRIC MACHINES. 85 



through all the parts of the revolving disc. The refrigerating 

 fluid is introduced at one end of the spindle, under pressure, 

 through a stuffing-box, circulates through the whole of the 

 induced system, and is expelled at the other end of the spindle. 

 The result of this cooling is to obtain a greater production 

 of electricity for a given size of dynamo-electric machine, but 

 it is obtained at the cost of complications in the construction 

 and the necessity of frequent repairs; that is the reason why 

 this arrangement has not found favour amongst the large 

 manufacturers of dynamo-electric apparatuses. The price of 

 Ml more machines is 2520 and 3780 francs for apparatuses 

 requiring 1 and 2 horse-power respectively. 



MISCELLANEOUS MACHINES. There exist a large number 

 of other systems of dynamo-electric machines, and new types 

 a i-f brought out every day. These machines being mostly 

 intended for electric lighting purposes, we will not give any 

 description or drawings of them ; they however differ very 

 little from the types actually in use, and offer no striking 

 peculiarity of such a nature as to give them any preponderance 

 over these types. 



We will only mention for the sake of information those 

 which were exhibited at the Paris and Vienna Electric Exhibi- 

 tions, and which appeared to us well designed : 



In the French section we noticed the Lontin machines, 

 with inducting wheels, and which had a certain success a few 

 years ago; and the Gerard machines, ingeniously devised for 

 laboratory experiments and for lighting ; 



In the American section the Edison machines, so appreciated 

 for lighting by incandescence, the Brush machines with rectified 

 currents, and the Maxim machines with Gramme bobbins ; 



In the English section, the machines of Ferranti, Elphin- 

 stone and Biirgin for the feeding of glow lamps, and of 

 Crompton arc lamp ; 



In the German section, the machines of Egger, Kremeneski, 

 Frenzel, Gravier, Giilcher, Hauck, Junger, Krottlinger, and 

 Osnaghi. 



SUPERIORITY OF DYNAMO-ELECTRIC MACHINES OVER BAT- 

 TKIUKS. We copy the following from the text of a lecture 



