188 Miscellanies. 
2. Notice of a Revolving Electro-Magnetic Instrument, by Dr. 
Bensamin Rusn McConne.u.* 
Mauch Chunk, Pennsylvania, June 25, 1837. 
Pror. Sintiman.— Dear Sir—Up to this date, I had entertained 
the hope of having ready for the ensuing number of the “ Journal 
of Science,’’ a digested series of “electro-magnetic experiments,” 
the results of some inquiry involving something of novelty at least, 
if not of much interest. The pressure of professional duty, how- 
ever, as colliery surgeon, and the physical character of my district, 
(which you are personally familiar with,) have hitherto prevented me. , 
I now. take advantage of a leisure hour, which after all may be too 
late for your next number, to place on record the subjoined facts, 
about which I confess I feel anxious. I have,—and have had for 
nearly a twelvemonth,—in operation, an electro-magnetic engine, of 
a construction and upon a principle essentially different from any 
thing hitherto announced. In the course of a series of galvanic 
‘experiments, which for several years past have assisted to beguile 
the intervals of professional labor, my attention was drawn to the 
mutual action of rectilineal and circular currents, as a highly prom- 
ising source of motive agency for practical purposes. After innu- 
merable failures, | eventually succeeded in constructing a machine 
which may be fairly pronounced perfect upon the actual scale of its 
construction ; its value upon a working scale remains to be proved. 
The general arrangement of my machine is not unlike the philo- 
sophical toy, invented, I believe, by Mr. Sturgeon, of London, as 
long since as 1828 or 9, of two copper discs, one at either end of @ 
common shaft, revolving each in its own trough of mercury, between 
the poles of two horse shoe magnets. Such is my machine in gen- 
eral, with the addition of a band or cog-wheel on the center of the 
same shaft, intermediate between the discs, which revolve between 
the poles of electro-magnets, without the intervention of a fluid 
medium of any kind as a part of the circuit; the mode of accom- 
plishing this constitutes the peculiarity of my claim, and you, sir, are 
competent to appreciate its novelty and its value. My electro-mag- 
nets are hollow, (another new feature,) and have been made with 
nearly eqewvalere results of bar iron, of tinned iron, and of copper- 
* Remark.—This letter was too late for the July No. of the Journal. We had 
hoped to give a figure of Dr. porated s machine, but have received no reply t “4 
an application for that t purpose. 
