308 Experiments upon the Induction of Metallic Coils. 
Art. X.—Experiments upon the Induction of Metallic Coils ; 
by Joun B. Zasrisxie, M. D. of Flatbush, L. I. 
Prof. Henry of Nassau Hall, Princeton, made the important 
discovery, that if an electric current be passed through a long coil 
of wire or metallic ribbon, the electricity was much increased im in- 
tensity.* This effect of a coil, although at first it may appear merely 
as a very curious fact, yet is a discovery of great importance, espe- 
cially in administering galvanism to animals, and in the construction 
of galvanic and electro-magnetic-apparatus. The intervention of a 
coil converts a calorimotor into a deflagrator, giving it the power of 
burning metals, decomposing fluids, giving shocks to animals, &c. 
In using galvanism for medical purposes, the coil is very conve- 
nient. It may be transported without any difficulty, and a simple 
galvanic arrangement consisting of a small plate of copper and zinc 
each, is sufaeiiet to charge a large coil. The effect of the coil upon 
the system is different fons that of an electrical machine or Leyden 
ial; it does not give a shock, but produces a spasm of the muscles, 
and if the circuit be repeatedly broken, or what is still more powerful, 
if this circuit be constantly reversed by means of the bascule of Am- 
pere, a constant succession of spasms is felt, which, with a coil of any 
size becomes insupportable, On this account the coil is more espe- 
cially indicated in rheumatism, palsy, and diseases of a similar na- 
ture, while the electricity of the Leyden jar is more powerful as a 
stimulant to produce absorption. But in the construction of gal- 
vanic apparatus, and in making electro-magnetic experiments, the 
coils of metallic ribbon are very valuable both in diminishing the ex- 
pense of the instruments, and lessening the Jabor of the experiments, 
while the convenience of their application is much greater than that 
of a number of wires, allowing a’ready alteration in the arrange- 
ment of the experiment, and of an easy mode of increasing the power 
of the apparatus merely by increasing the length of the coils. 
Galvanometers may be constructed upon this principle by sur- 
rounding the needle with a coil of metallic ribbon. An instrument 
constructed in this manner has been used by the author for a long 
time, and is found to be quite as sensible as the ordinary galvan- 
scope to small galvanic currents, and much more powerful when 
the current is large. It consists of a needle suspended upon a pivot, 
omp with a‘coil of zinc ribbon one half an inch wide 
* ee ae American Journal of Science, for July, 1832. 
