REPORT OF MR. ROBERT B. LINES.
449
The arrangement is shown in Plate VI. : l is the lever of the
Plate VI.
switch, a heavy piece of iron, which is turned through a semi-circle in order to change the position of the rails on which it acts, the connection not being shown in the diagram. On being turned from right to left it presses against the stout metallic spring s , which is insulated from the ground and connected (in the apparatus in question by a subterranean wire) to the magnet m, and through it to the battery g at the station. The switch-lever being connected with the ground, thus closes the circuit of the battery, which acts upon the electro-magnet, b shows the position of the magnet m as it stands in the box c, which is placed against the wall of the station. Between the poles of the electromagnet a permanent magnet d is hung, with its poles so arranged as to be attracted in the direction of the dotted lines when the electro magnet is influenced by the current from the battery g. The axis of the permanent magnet is carried up through the card-board e to the point h, where a needle i is secured to it at right angles to the permanent magnet d. The position of the main and side tracks is traced on the card-board.
The apparatus being thus shown, its operation will be easily understood. As soon as the switch-lever is thrown over to change from main to side track, it presses against s, closing the circuit. The electro-magnet m attracts the permanent magnet d, which swings from left to right, carrying with it the needle i, which is thrown over to the point f. The position of the switch is thus indicated in the clearest manner at the station.
There is another interesting and useful instrument in the Italian department, employed on the upper Italian railway 57