The point of the siphon does not touch the paper, although it is very
close. It would impede the motion of the coil if it did. But the
'capillary attraction' of so fine a tube will not permit the ink to flow
freely of itself, so the inventor, true to his instincts, again called
in the aid of electricity, and electrified the ink. The siphon and
reservoir are together supported by an EBONITE bracket, separate from
the rest of the instrument, and INSULATED from it; that is to say,
electricity cannot escape from them to the instrument. The ink may,
therefore, be electrified to an exalted state, or high POTENTIAL as it
is called, while the body of the instrument, including the paper and
metal writing-tablet, are in connection with the earth, and at low
potential, or none at all, for the potential of the earth is in general
taken as zero.
The ink, for example, is like a highly-charged thunder-cloud supported
over the earth's surface. Now the tendency of a charged body is to move
from a place of higher to a place of lower potential, and consequently
the ink tends to flow downwards to the writing-tablet. The only avenue
of escape for it is by the fine glass siphon, and through this it rushes
accordingly and discharges itself in a rain upon the paper.
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