he cylinder revolves, the wheels are carried around with its
shaft and current impulses flow through the wires to the magnets as the
brushes make contact with the metallic segments of these wheels.
One example will be sufficient to convey to the reader an idea of the
operation of the apparatus. Assuming, for instance, that it is desired
to send out the letters AM to the printer, let us suppose that the pin
corresponding to the letter A is at one end of the cylinder and near the
upper part of its periphery, and that the letter M is about the centre
of the cylinder and near the lower part of its periphery. The operator
at the keyboard would depress the letter A, whereupon the cylinder would
in its revolution bring the first-named pin against the key. During
the rotation of the cylinder a current would pass through wheel W' and
actuate TM, drawing down the armature and operating the escapement,
which would bring the type-wheel to a point where the letter A would
be central as regards the paper tape When the cylinder came to rest,
current would flow through the brush of wheel W to PM, and its armature
would be attracted, causing the platen to be lifted and thus bringing
the paper tape in contact with the type-wheel and printing the letter A.
The operator next sends the letter M by depressing the appropriate key.
On account of the position of the corresponding pin, the cylinder would
make nearly half a revolution before bringing the pin to the key. During
this half revolution the segmental wheels have also been turning, and
the brushes have transmitted a number of current impulses to TM, which
have caused it to operate the escapement a corresponding number of
times, thus turning the type-wheels around to the letter M. When the
cylinder stops, current once more goes to the press-magnet, and the
operation of lifting and printing is repeated. As a matter of fact,
current flows over both circuits as the cylinder is rotated, but the
press-magnet is purposely made to be comparatively "sluggish" and the
narrowness of the segments on wheel W tends to diminish the flow of
current in the press circuit until the cylinder comes to rest, when the
current continuously flows over that circuit without interruption and
fully energizes the press-magnet. The shifting of the type-wheels is
brought about as follows: On the keyboard of the transmitter there are
two characters known as "dots"--namely, the letter dot and the figure
dot. If the oper
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