e 
346 On Ellectro-magnetism as a Moving Power. 
The experiments here were not such as could be performed 
upon the laboratory table; but were with large masses of iron, 
: weighed six hundred pounds. When this engine was first tried, 
iL > 
with the same battery which had before given me one-fifth of as 
ticularly to the cut-off, which was a very different thing now 
from what it. had been in smaller engines, the engine soon yielded 
one horse power. . Here was a gain of eighty per cent. as meas- 
ured merely by the size of the battery. But it was much more ; 
for the cost was found to be less for one horse power than it had 
been before for one-fifth of a’horse power, ina smaller, engine ; 
how much less has not yet been ascertained. 2 eee 
A great variety of experiments were continued with this engine, 
to be hereafter detailed, each having a ans “objegt; and, t . 
am happy to say, each resulting advantageousfy, .so that finally, 
by little daily increments, I obtained from this engine, by a tri- 
fling addition of battery, a full two horse power. ce 
way of giving a practical character to the engine, it was 
geared toa circular ‘saw ten inches diameter, the turning-lathe 
and grindstone of the workshop, all of: which it worked simulta- 
neously, as witnessed by a number of visitors, and, if I mistake 
not, by your ecessor in office, in company with Lieut. Maury, — 
of the National Observatory. 
After many satisfactory trials with this engine, it was taken 
down, and all its available parts used in the construction of the 
single horizontal engine which I had the honor lately to exhibit 
‘ore the Smithsonian Institution. This change was © 10K 
the purpose of dispensing with the dead weight of one of the 
driving bars, and more particularly for introducing the important 
