NEW STYLE OF FIRE ALARM SYSTEM.
MR. L. G. Wooley, of Kenton, Ohio, has invented, and the National MagnetoElectric Telegraph company, of Springfield, Ohio, manufactures a fire alarm system which needs neither batteries nor contacts. It so operates that a sudden, rapid, single half-turn of an ordinary single coil magneto armature in the field of a powerful magnet sends out upon the line connected with it a current impulse which maybe raised to any potential desired. Beginning, first, with the call-boxes, which are distributed about the town on a series-circuit, or upon a number of circuits, these instruments are entirely self-contained. In each is a spring, which is wound up by the fire chief when he sends in the “fire-out” signal. Introducing a key into the box and turning it liberates a short train of powerful clock-wheels geared to the armature of a strong magneto in such a way that the latter is given a series of half turns corresponding to the number sent out by the box. The turning of the armature is accomplished by a lever and ratchet system, operated by a cam driven by the main spring and cut into such shape as to send the predetermined signal from its particular box. At the receiving station is placed a polarised electro mechanical gong, or relay, as may be desired, or the functions of the two may be combined, as is well shown in fig. 3. This represents a circuit of fire alarm boxes connected with an electro-mechanical gong, shown at C, which acts also as mechanical relny. It will be noticed that the levers G and H connect the striking hammer of this gong with the armatures of a number of magnetos, which may be connected either to such apparatus as is shown, or to any other form of repeating apparatus that may be desired. In figs. 1 and 2 is shown an apparatus used to test the continuity of the circuit on which the boxes are placed, and which instantly indicates should the latter be open. A powerful magneto, shown at the top of the illustrations, has its armature coupled by means of the lever, Q, the connecting rod, P, and the rod, O. to the weight hung from the lever, U. On the back of the machine, as shown in fig. 1. is a clockwork connected with an escapement, which continually turns the wheel, M, upon the edge of which are rollers engaging with the rod. O, and through it gradually forcing the armature of the magneto to the position indicated in fig. 2. This wheel revolves so that one of its rollers passes the end of the rod, O, about every two minutes. As soon as the roller passes, the weight tends suddenly to jerk the armature back to the position indicated by dotted lines, but, since the apparatus is connected through the closed circuit of boxes, the resistance offered to the flow of current in the armature circuit is so great that the apparatus settles quietly back without producing energy sufficient to ring the bells in circuit.
Should, however, the circuit be open, there will be no resistance to the movement of the armature, and the weight will descend suddenly, striking the upper end of the vertical rod, V, which is attached to a bell, as shown. This gives its warning signal for open line, and continues to give it every two minutes, until the line is repaired. Should a number of circuits of boxes enter the same station, a simple commutating device will readily connect them in turn to this testing apparatus, which may then be speeded up. if desired, so that each line is tested at regular and short intervals.
It will be seen, from the foregoing description that this system is entirely independent of batteries, and that, on account of the large energy that may be imparted to the magnetos currents of greatstrength can be used and long circuits worked, or, by the aid of the repeating mechanism shown in fig. 3, even large tower bells may be struck. As will be noticed, there is not an open contactany where in the system, nor is there anywhere a contact of the operative variety to keep clean, or rather to get dirty and out of order at the moment when it is most needed. The system is of such great simplicity and extraordinary ingenuity as to recommend itself highly to those practically concerned in fire alarm apparatus.