442
EXPOSITION AT VIENNA.
no longer attracted, is drawn up by the tension of a spring attached to its lower arm.
Fixed to the armature, on its upper side, are two arms which sustain a lever. On the rising of the armature and lever the latter releases a wheel which it allows to make one revolution, upon which it falls into its normal position. This wheel gears into a larger notched wheel, turned by a weight, the gears in such relation that the larger w T heel advances one notch to each revolution of the smaller. These notches lift an arm having a hammer at its extremity, which strikes upon a large bell. It also operates another arm provided Avith a punch, which perforates a sheet of paper passing betiveen rollers. The number of signals given upon the bell is thus accurately registered on the paper.
The registering part of the apparatus is called the "control,” which term, hoivever, is used in Europe indifferently, to designate a register of signals at the receiving station, or an automatic acknoAvledgment returned to the sending station. It is also applied, at least by the French, to the motive-power, or "controlling” force.
The system Leopolder, Avith the " control ” attachment, is exhibited in the separate " Nordbahn Ausstellung,” or collection of the Northern Railway of Austria. It having been introduced into Italy before the adoption of the "control,” the latter Avas added, in substantially the same manner, by Sig. Montelli, one of the engineers of the Alta Italia Railway. In addition to this, however, a further modification Avas introduced by Sig. Montelli, and the apparatus, thus modified, is on exhibition in Group XIV. of the Italian department.
Plate II.
A When the bell-lever l
(Plate II., A) falls to deliver the stroke, it carries Avith it a catch i, Avliich strikes against a tooth of the ratchet-wheel c, and carries it fonvard one tooth. The wheel is prevented from turning farther by a spring a, held against it by the tension of the spiral m.