other portions of the key-board, and the current then passes from the
terminal C to M, and there bifurcating, one portion of it goes to the
bobbins of the apparatus and thence to the earth, while the other goes
to actuate the correspondence apparatus. The index-hands of the two
apparatus thereupon begin their movement simultaneously, and only stop
when the pressure is removed from the button and the current is
consequently interrupted. H is a ratchet-wheel, which, like the
key-board, is insulated from the rest of the apparatus. The button, K,
located over each of the dials, serves to bring the index-needles back
to their position under the cross shown in Fig. 12. The key, X, serves
for winding up the clock-work movement.

_The Annunciator Apparatus._--This apparatus, which performs the same
role as the one just described, is simply an ingenious modification of
the annunciator used in hotels, etc.

It consists of a wooden case, containing as many buttons as there are
phrases to be exchanged. Over each button, b, there is a circular
aperture, behind which drops the disk containing the phrase. Between
the buttons and the apertures are rectangular plates, P, in which are
inscribed the answers given by pressing on the button of the receiving
tablet--a pressure which, at the same time, removes the corresponding
disk from the aperture. Two disks located at the upper part carry
these inscriptions: "Error, I repeat;" "Wait." The tablets on
exhibition have eight disks, and can thus be used for exchanging six
different phrases. In the interior, opposite each aperture, there is a
Hughes magnet, between the arms of which there oscillates a vertical
soft-iron rod, carrying a disk. The maneuver "is simple." By pressing
upon a button there is sent into the bobbins of the magnet
corresponding to this button a current which causes the disk to appear