IHR. C. V. WALKER ON MAGNETIC STORMS AND EARTH-CURRENTS. 109 
this line ; when, however, they are observed, they always confirm the law as to direction^ 
but always fall far below the Ramsgate — Margate in value. I have had only a solitary 
instance to quote in all four sections of Table XII., and this was of doubtful (1) value. 
A^t the length in one case is only three miles, and in the other twenty-six miles, in which 
latter, therefore, a greater rather than a less derived current might have been expected, 
and the more so as its galvanometers happen to be better. 
Then, again, on comparing the respective values of the currents collected by the Mar- 
gate — Ashford and the Ashford — Hastings wii’es, we find the same apparent contradic- 
tions. The former is 9° and the latter 11° from the determined direction, the angular 
distance differing by only 2° ; yet the currents in the latter are invariably marked as 
“ slight ” and “ middling,” when those in the former are “ strong ” and “ very strong ” 
(see Table XII.). There is no material difference in mileage. 
Again, the bearing of the London — Dover line is the same as that of the Reading — 
Red Hill. Cmuents, some even of high value, are frequent in the former, but have been 
rarely noticed, and then only in very small amount m the latter. 
These apparent anomalies lead to the conclusion that the amount of current travel- 
ling through the substance of the earth during a magnetic storm is not the same in all 
parts of a large district ; and this must needs be the case. The more favourably the con- 
ducting materials may be disposed in the geological strata of a district, the greater the 
value of the current-drift along the same may be expected to be. AVhere the materials 
are of inferior conducting power and ill arranged, there will the current that is present 
have a lower value. In fact these currents travel, as might be anticipated, in the con- 
ducting mass of the earth, just as they travel in all other conductors, and adjust and 
distribute themselves according to the known laws of resistance. 
In Stuegeox’s ‘ Annals of Electricity,’ vol. i. p. 124, is a paper by Mr. Henwood “ On 
the Electric Currents observ^ed in some Metalliferous Veins,” a discovery which the 
author rightly attributes to Mr. Fox*. In the ‘Annual Reports’ of the Royal Poly- 
technic Society of Cornwall for 1836, 1841. and 1842, are reports “On Mineral Veins,” 
by Robeet AVeee Fox, and “ On the Electricity of Mineral Veins,” by Robeet Hunt 
and Professor Phillips. It is more than probable that the electric currents which were 
found by these gentlemen to be traversing the metallic veins in the mines of Cornwall, 
were in many instances portions of great floods of electricity, drifting along the district 
in which the mines were placed, forming in fact a portion of larger disturbances attend- 
ing on magnetic storms. The derived currents which were collected by their galvano- 
meters gave the same contradictory results as to direction that come out from any of 
our own cases, looked at individually ; but in the papers before me I have no sufficient 
data from which to make groups of observations, in order to arrive at probable directions, 
nor do I gather whether changes of direction were noted. My impression is that I have 
heard of the value of currents being different, collected at different times at the same 
places. It would have been instructive, had it been possible, to compare some of the 
* Philosopliical Transactions, 1830, p. 399. 
