At 6, P.M., the line between Boston and New Bedford (sixty
miles in length) could be worked only at intervals, although, of
course, no signs of the aurora were apparent to the eye at that hour.
The same was true of the wires running eastward through the State of
Maine, as well as those to the north.
The wire between Boston and Fall River had no battery upon it Sunday,
and yet there was an artificial current upon it, which increased and
decreased in intensity, producing upon the electromagnets in the
offices the same effect as would be produced by constantly opening and
closing the circuit at intervals of half a minute. This current, which
came from the aurora, was strong enough to have worked the line,
although not sufficiently steady for regular use.
The current from the aurora borealis comes in waves,--light at first,
then stronger, until we have, frequently, a strength of current equal
to that produced by a battery of two hundred Grove cups. The waves
occupy about fifteen seconds each, ordinarily, but I have known them to
last a full minute; though this is rare.
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