140 Double Avial Reciprocating Engine. 
out abandonment is the strongest possible testimony in favor of 
an inventor, I have resorted, with your indulgence, to the pages 
of this Journal, to establish the date and nature of my invention, 
and to give due caution to all as to its use in any way to engender 
liability. Although I cannot, without resigning my office, enjoy 
the usual rights of inventors, yet I have every reason to believe 
that Congress will, by special act, authorize me to receive and 
hold a patent for this and some other kindred inventions. 
The use and action of the galvanometer will readily explain 
the basis of the double engine. The power of the helices is 
much better displayed when the U form bar is used instead ofa 
straight bar of iron, as in the first engine. As the straight bar 
reaches its equilibrium with the helix, when its projecting por- 
tions are of equal length, or rather when the centre of the helix 
exactly coincides with the centre of the bar, it was plainly infer- 
rible, that the U form bar would be drawn through the helices 
until they were both intercepted by the bend of the bar. This 
was fully verified by experiment, as follows. A bar of iron of 
this form, having its legs ten inches in length, was mounted upon 
a sliding frame—part of its weight counterpoised, and its legs 
inserted into twovhelices of three inches length ; the helices were 
then connected with the battery, and the bar was drawn through 
the helices until they rested upon its bend. Thus with a single 
pair of helices and a single bar of iron, a continuous impulse was 
given through the space of ten inches, affording at once the ele- 
ments for the most simple and efficient exhibition of magnetic 
power as a propelling agent. The power, as measured by the 
axial galvanometer, averaged in this experiment 13 pounds 
through the ten inches; in the last half inch, or that near the 
bend, the power was two ounces, and at the point of greatest 
action it was 33 pounds. I find, moreover, that the helices, if 
properly suspended, will pass over the entire length of two feet ; 
though, from the difficulty of magnetic induction through such 
long bars, the power is feeble through a considerable portion of 
the-space. The machine represented. by fig, 2, has six inches 
stroke, and although its mechanical power has not been abso- 
lutely tested, yet, for the elements employed, it is by far the most 
powerful engine of the kind I have seen; and its operation is sO 
encouraging that Iam preparing for anothae engine, of one foot 
stroke. Upon inspecting the figure, the whole arrangement, 
which is very simple, will be understood at a glance. The U 
