450
EXPOSITION AT VIENNA.
for the purpose of indicating to their principal stations from points outside at which several tracks diverge, the direction from which a train is approaching.
Having been unable to secure a plan of this apparatus, or to open it in order to make a sketch, I can only present its external appearance. Its construction, however, will be readily understood by those familiar with the application of electro-magnetism as a motive force.
At the station A Plate VII. (Milan) is an apparatus consisting of a sonnerie a trembleur and a flat case or box hung on the wall in the office of the station-master. The case
Plate VII.
Sonner#*
is connected by three wires to three circuit-closers a, b and c at the junction, and by a fourth to a sonnerie which serves as a " control ” for the signal-man.
On the arrival of a train, say from Pavia, the signal-man presses down the button at a, throwing the current from the battery g upon the line. The circuit is through an electromagnet in the case, thence through the magnet of the trembling-sounder to the ground. The magnet in the case turns a disc so as to display the word " Pavia ” at the window of the case, and at the same time the sonnerie rings, attracting the attention of the station-master. The latter, by putting down the ring a, returns the disc to blank, arrests the ringing of his own bell, and at the same time closes the circuit of the fourth wire to B, thus indicating, through the sonnerie at that point, that the signal has been received and understood.
The battery g may of course be placed at the station as well as at the junction.
I have been much indebted to the courtesy of Sig. Orestes Lattes, an engineer of the Alta Italia Kail way, and a member of the Italian Commission and International Jury, for facilities given me for the examination of the interesting exhibit made by his company.
An apparatus of a totally different character from the others of this class, and in some respects of entirely novel construe-