REPORT OF MR. ROBERT B. LINES.
447
into by another, has caused in Europe the very general introduction of electrical apparatus for its prevention.
The system of Mayer & Wolff, telegraphic instrument- makers of Vienna, which has been adopted and is exhibited by the Nordbahn Railway of Austria, is one of the simplest of this class, belonging to subdivision a. The semaphore is a disc of the ordinary class, which is turned from the station in the usual manner by a crank and wire. Around the support of the semaphore is a small circular box of metal, used to protect the connecting points of an electric circuit from exposure to the weather. As the semaphore turns to the position of arrest, a projection upon one side of the support touches within the box a brass spring, which is insulated from the semaphore and its metal support, and connected by a wire to the battery at the station. The support itself is connected with the ground, and thus an electric circuit is formed. Plate IV. illustrates the arrangement.
Plate IY.
Station
In circuit at the station is a trembling-sounder, which rings us long as the disc is in position, of arrest and the projection °n its support touches the spring. One of the advantages claimed for this particular apparatus is, that the bell does not commence to ring until the disc is very near the position of arrest, thus rendering false or accidental signals improbable.
Where the semaphore adopted is an arm instead of a disc, it is evident that by changing the position of the connecting points from the side of the support to the top near the fulcrum °f the arm, the above system could be used equally well. In