STURGEON’S IMPORTANT EXPERIMENTS. 
589 
ON ELECTRO-PULSATIONS AND 
ELECTRO-MOMENTUM. 
By William Sturgeon, 
Lecturer on Experimental Philosophrj at 
the Honourable East India Company's 
Military Academy, Addiscombe, 
It is very well known to the readers of 
the Philosophical Magazine, that I have 
long considered electric currents, when 
transmitted through inferior conductors be- 
tween the poles of a voltaic battery, as the 
effect of a series of distinct discharges, in 
such rapid succession as not to be individu- 
ally distinguished by the senses. Such 
currents I have called electro-pulsatory. 
See my theory of magnetic electricity in 
the London and Edinburgh Philosophical 
Magazine, vol. ii. p. 202. 
By following up these views of electro- 
pulsations, I was about two years ago 
enabled to dispense with all acid or saline 
liquids, in the employment of galvanic bat- 
teries, for the purpose of galvanizing, as it 
is called, either to satisfy the curiosity or as 
a medical process ; and my plan, which 
answers very well, I have found to be pro- 
ductive of a considerable saving in the ex- 
pense necessarily attendant on the use of 
voltaic batteries when excited by acid solu- 
tions. 
It is well known that a Cruickshank 
battery of about a hundred pairs will, by 
employing water alone in the cells, charge 
to a certain degree of intensity almost any 
extent of coated surface of glass that we 
please ; and that the same degree of charge 
is given to it by a single contact of the con- 
ductors, however short its duration. This 
being understood, and understanding also 
that the shock produced by any discharge 
from a given intensity would be propor- 
tional to the quantity of fluid transmitted in 
a given time, it was easy to foresee that a 
series of shocks in rapid succession might 
be produced by some mechanical contriv- 
ance, and that the degree of force might 
be regulated by varying the extent of coated 
surface. 
My first experiments were made with a 
hundred and fifty pairs of three-inch plates, 
and about seven feet on each side of coated 
glass ; and ray apparatus for producing a 
rapid succession of shocks was one of Mr. 
Barlow’s stellated electro-raagnetic wheelsf 
which was soldered to an iron spindle and 
put into rotatory motion by a wheel and 
• Communicated by the Author, 
t [See Phil. Mag., First Series p. xi. vol 
lix, 241. -Edit.] 
band ; the points of the wheel touching in 
succession a copper spring in connexion 
with the positive surface, and thus producing 
a discharge at every contact of the wheel 
and copper spring. 
When the two surfaces are connected by 
wires with two basins of salt water, and the 
hands immersed one in each basin, the effect 
experienced is precisely that of the dis- 
charge of a voltaic battery. Tlie discharges 
can be made in such rapid succession as to 
prevent the sensation of distinct shocks ; 
and if the process were to be concealed it 
would require some experience to distin- 
guish be tween the effects on the animal 
oeconomy from this apparatus and those 
from a voltaic battery charged with acid 
and water. 
My views being so far verified, the next 
attempt was to simplify the apparatus and 
make it more portable ; and as it was rea- 
dily seen that if one hundred pairs would 
charge glass of considerable thickness, 
thinner glass might be charged by fewer 
pairs ; this was done ; and eventually the 
glass entirely dismissed, and its place sup- 
plied with well-varnished Bristol-board. 
These boards answer exceedingly well as a 
reservoir for low intensities ; they may be 
coated to within an inch of the edge all 
round, and placed upon their edges either 
on a piece of glass or on a board properly 
prepared, and arranged to any required ex- 
tent like the plates of a voltaic battery, but 
when considerable intensity is wanted, it is 
better to use thin glass. 
From these facts we learn that metallic 
surfaces of many acres of extent may possi- 
bly be charged to a low intensity in the in- 
terior of the earth, by having a thin inter- 
vening stratum of inferior conducting mat- 
ter sufficient to insulate from each other 
their dissimilar electric surfaces. 
It may now be understood that the 
slightest accident which would suddenly 
break through the insulation, such as the 
sinking of a mass of metalline matter from 
one stratum to the other, would cause a 
sudden rush of an immense ocean of the 
electric fluid, which might be productive of 
subterranean lightenings and tremendous 
explosions sufficient to shake an extensive 
range of country on every side. 
^ Connected with the preceding facts there 
are others which may be conveniently men- 
tioned in this place, and which would lead 
us to similar explanations of the causes of 
subterraneous convulsions. Electric cur- 
rents of considerable magnitude when sud- 
denly checked, or diverted to a new chan- 
nel, produce a momentum not very genrally 
understood ; but which I will endeavour 
to explain. A coil of copper wire excited 
