352 NOTICES OF THE MEETINGS [Jan. 20, 
With these lights it is interesting to look at the measured 
velocities of electricity in wires of metal, as given by different 
experimenters. 
Miles per second. 
* Wheatstone in 1834, with copper wire made it 288,000 
* Walker in America with telegraph iron wire - 18,780 
* ©’ Mitchell, ditto. = ditto. - - 28,524 
* Fizeau and Gonnelle (copper wire) - - 112,680 
* Ditto. - - (iron wire) - - - 62,600 
+ A. B. G. (copper) London and Brussels Telegraph 2,700 
t+ Ditto. (copper) London and Edinburgh Telegraph 7,600 
Here, the difference in copper is seen by the first and sixth 
result to be above a hundred fold. It is further remarked in 
Liebig’s report of Fizeau’s and Gonnelle’s experiments, that the 
velocity is not proportional to the conductive capacity, and is 
independent of the thickness of the wire. All these circumstances 
and incompatibilities appear rapidly to vanish, as we recognise and 
take into consideration the lateral induction of the wire carrying 
the current. If the velocity of a brief electric discharge is to be 
ascertained in a given length of wire, the simple circumstances of 
the latter being twined round a frame in small space, or spread 
through the air through a large space, or adhering to walls, or 
lying on the ground, will make a difference in the results. And 
in regard to long circuits such as those described, their conducting 
power cannot be understood, whilst no reference is made to their 
lateral static induction, or to the conditions of intensity and quantity 
which then come into play; especially in the case of short or 
intermitting currents — for then static and dynamic are continually 
passing into each other. 
It has already been said that the conducting power of the air 
and water wires are alike for a constant current. This is in 
perfect accordance with the principles and with the definite cha- 
racter of the electric force, whether in the static or current or 
transition state. When a voltaic current of a certain intensity is 
sent into a long water wire, connected at the further extremity 
with the earth, part of the force is in the first instance occupied 
in raising a lateral induction round the wire, ultimately equal in 
intensity at the near end to the intensity of the battery stream, 
and decreasing gradually to the earth end, where it becomes nothing. 
Whilst this induction is rising, that within the wire amongst its 
particles is beneath what it would otherwise be; but as soon as 
the first has attained its maximum state, then that in the wire 
becomes proportionate to the battery intensity, and therefore equals 
that in the air wire, in which the same state is (because of the 
* Liebig and Kopp’s Report, 1850 (translated), p. 168. 
t+ Athenzum, 14th January, 1854, p. 54. 
