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G. Mathiot on the Atlantic Cable. 159 
extent of surface, and the thinness and nature of the insulation, 
(the dielectric); the time required for charge is determined by 
the quantity to be conveyed, the resistance of the conductors 
and the difference of the tensions, and the further resistance due 
toa certain constant, dependent on the nature of the electric 
medium, (its coefficient of elasticity,) which is wholly undeter- 
mined so far, and probably can not be handled before we obtain 
conducting lines of many thousand miles in length, but which is 
so small that it may be disregarded in all practical applications 
of electricity: in which we may make the expression of the 
T—t 
oR) . 
Q the quantity required, and £& the resistance, and we certainly 
have the means of increasing or diminishing it to the extent of 
our ability to handle the generating electrical apparatus, up to 
the point of fusion of the conductor. By Ohm’s principles, and 
also by the demonstrated experiments of Coulomb, when a sur- 
face charged to any given intensity is brought in contact with 
another surface the electricity is distributed between them and 
the tension falls in proportion to the combined surfaces divided 
by the first surface; the time to convey a given quantity of 
electricity into a given surface will depen therefore on the extent 
of the first charged surface and the tension of the charge, with 
the resistance to conduction. As the quantity of electricity 
. i Big 
flowing from Sto s at any moment after contact will be —>- and 
br time for passing the whole quantity or producing equilibrium 
= will be dependent on the quantity to be passed, and 
time the ratio of a fraction ( where 7, ¢, are the tensions, 
R come 
as this latter is aa it is evident that the whole time for charge 
5 $ i 
1s dependent on the value for Sas well as of s and the tension 
of the source; and that therefore the time in the problem of the 
conveyance of a given quantity of electricity from a charged 
po Sto a recipient surface s will be a decreasing function 
0 
S, 
The Atlantic cable is a Leyden battery of over four acres of 
e electrical 
arrangements for working the cable I cannot learn, but on kine 
robably 
. 
sie 
Abs 
os 
ay 
