The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

170 STEINHEIL S ELECTRIC TELEGRAPH.
ulated. that their motion is perfectly free and easy. In the
frames of the multiplier there are 600 turns of the same insulated copper wire as was employed for the inductor. The commencement and the end of this wire are shown at M M, fig. 12.
The magnetic bars are, as the figures show, so situated in the
frame of the multiplier, that the north pole of the one is presented to the south pole of the other. To the ends which are
thus presented to each other, but which, owing to the influence they mutually exert, cannot well be brought nearer,
there are screwed on two slight brass arms, supporting little
cups, figs. 13 and 14. These little cups, which are meant to
Fig. 14.
be filled with printing ink, or black oil color, are provided with
extremely fine perforated becks, that are rounded off in front.
When printing-ink is put into these cups, it insinuates itself
through the bore of these becks, in consequence of the capillary
attraction, and without running out, forms on the openings of
the becks a projection of a semi-globular shape. The slightest
contact suffices, therefore, for writing down a black point or dot.
When the voltaic influence is translmitted through the multiplying wire of this indicator, both magnetic bars make an effort
to turn in a similar direction upon their vertical axis. One
of the cups of ink would, therefore, advance from within the
frame of the multiplier, while the other would retire within it.
To prevent this, two plates are fastened at the opposite ends of
the free space that is allowed for the play of the bars, and
against whicl the other ends of these bars press. Only the
end of one bar can, therefore, start out from within the multiplier at a time, the other being retained in its place. In order
to bring the magnetic bars back to their original position as
soon as the deflection is completed, recourse is had to small
moveable magnets, whose distance and position are to be varied,
until they produce the desired effect. This position must be
determined by experiment, inasmuch as it depends upon the
intensity of the current called into execution.
If this apparatus be employed for producing two sounds
easily distinguishable to the ear by striking on bells, it will be
right to select clock-bells or bells of glass, both of which easily
emit a sound, and whose notes differ about a sixth. This in-/
terval is by no means a matter of indifference. The sixth is
more easily distinguished than any other interval; fifths and