ELECTRIC GENERATORS. 107 



Polytechnic Institution in London, had a boiler seventy- 

 eight inches long, and forty-two inches in diameter, with 

 forty-six steam jets. It gave sparks twenty-two inches 

 in length, and charged to its full capacity, in six to eight 

 seconds, a Leyden battery, having eighty square feet of 

 coated surface. 



Another one, described by Noad, had one hundred 

 and forty steam jets, gave sparks of the same length, 

 with thrge or four times the rapidity; and charged, to 

 its full capacity, a Leyden battery having 1,188 square 

 feet of coated surface, sixty times in a minute. 



But though capable of such powerful effects, this 

 machine is not practical. It is inconvenient to manage, 

 requires distilled water, careful cleansing of the boiler 

 after use, and great steam pressure. Its operation is 

 accompanied with a deafening noise, and the escape of 

 a great volume of steam, producing dampness and other 

 unpleasant results, when used in a room. Hence its 

 chief value is in the demonstration of the important 

 fact, that electricity may be generated in this way. 



