136 Electricity in Machinery. 
horizontal band at the moment the narrow one was slipped from 
the motor wheel upon the free pulley, the part of it connecting 
the upper part of the drums was observed to relax, while that 
connecting their lower surfaces, from being curved downwards 
by its weights became proportionally tense. In the first case, the 
upper part of the band was made tense by the great amount of 
friction in the machinery which it had to overcome, and of course, 
the friction of the band upon the drums was increased in the 
same ratio. But when the free pulley only was turned, the fric- 
tion to be overcome, and consequently that of the bands, was 
much diminished ; and this increased amount of friction of the 
bands upon the drums in the first case, is to be referred to as the 
exciting cause of the electricity. 
From this statement you will observe that there was no friction 
of the bands upon each other as is mentioned in the article referred 
to above, since the horizontal bands were parallel and the-vertical 
ones eight inches apart at their nearest approximation. In another 
part of the manufactory, however, two portions of a band were 
observed which were crossing and rubbing upon each other, but 
their friction was attended with no observable electrical effects. 
At this time however the band was passing around a free pulley ; 
I was therefore led to inquire as to its electrical state during the 
motion of its machinery, and ascertained that its attractive power 
for cotton, &c. at such times was as great as in that of the bands 
Although these facts do not authorize us to dispute those in 
Mr. article, yet they naturally suggest the question whether 
the electricity in that case was not excited by the friction of the 
band upon the wheels rather than upon each other, and if 80, 
whether the apparent difference between the bands below their 
junction and above was not in reality caused by the application 
of the jar in the one case to a tense, and in the other to a relax 
portion of the band. 
Not being intimately acquainted with the action of electrical 
apparatus in different circumstances, I am unable to say whether 
_ increased pressure of the whole flap of the common machine upon 
the cylinder would materially increase the amount of electricity 
_ developed, but from the above facts, as well as the nature of the 
_ @ase, I should suppose it would, and if so, the circumstance prop- 
rly attended to in the construction of electrical machines, would 
em, cateris paribus, much more powerful. 
