Fig. 1,031.—General Electric thermal flasher. It consists of a small brass cylinder fixed at its left hand end to one of the terminal blocks. The junction between the two is hidden by a portion of the cover, which is shown broken away. The right hand end of the cylinder carries a cross piece bearing a platinum contact; and opposite this is the platinum tip of a contact screw carried in the other terminal block. The cylinder is wound with a heating coil of manganin resistance wire, one end being soldered to the cylinder and the other to the right hand terminal. When the current is switched on, the coil and the cylinder warm up and the cylinder elongates sufficiently to make contact and light the lamps. The coil being then short circuited, it and the cylinder cool down, and contact is broken, whereupon the coil is put in circuit once more, and warms up again. In some sizes of this flasher, the contact gap is shunted by a small condenser fitted beneath the base. This helps to eliminate the sparking at the contacts.
Carriage Calls.—These are used to avoid the confusion and noise at the theatre, club house or department store when vehicles are called by a megaphone.
Fig. 1,032.—Monogram or unit for carriage call or talking sign. It consists of a collection of metal compartments each arranged to receive an incandescent lamp. The purpose of these compartments is to confine the light to a certain space, thus forming a clearly defined number or letter which can be read from a distance.
