New Fire Alarms.
A few years ago, says La Nature, we described the fire alarms that were being put in service in the streets of Paris. It was a question of an alarm upon a column, due to Mr. Petit, and in which a button pressed by a person asking for help actuated a bell and a clockwork that gave a signal at the engine house along with the number of the alarm brought into play. While offering decided advantages, this system was defective in some points. The firemen always had to proceed to the alarm whence the signal came in order to ask exactly where the fire was, and they did not know its nature.
So, while installing the Petit apparatus, the fire department, and particularly its eminent engineers. Commandant Krebs and Captain Cordier, set about to find something better. The ideal was to be able to permit the public to telephone to the engine houses all the details of the location, extent and nature of the fire. Unfortunately, the practice of telephony is still unfamiliar to many persons, and consequently what was necessary was an absolutely automatic apparatus that would attract the attention of the station by a bell, making known to the person calling that the indications given were understood. A very ingenious apparatus, due to Mr. Digeon, has been under trial for some time, and, having proved successful, has been rapidly put in service in a large number of quarters.
As to external aspect, this new apparatus differs but little from the Petit system. Like it it comprises a square box painted red, mounted upon a column in the shape of a lamp post. The alarm and telephone, inclosed in the box, communicate, through wires running to the interior of the column, with two cables coming from the central station through the sewers. Let us walk around the apparatus : Here is the door, into which is set a small glass. At the top of the door we read : “ In case of fire, break the glass and then cry out distinctly in the mouthpiece of the telephone the nature of the fire, the street, and the number.” The normal type of alarm is provided with a small hammer like a door knocker, which permits of effecting the breakage of the glass, but this has been removed, since it gives rise to mistakes. Let us strike hard, as auolher inscription tells us to, and, according also to these same instructions, the door will open and reveal the mouthpiece of the telephone placed in the interior. This opening, in fact, reveals itself to us at the bottom of the box, surrounded by the inscription in exergue : “ Mouthpiece of the telephone.” The directions are intelligently multiplied throughout the apparatus, and the most excited person cannot fail to see them. When the door opens, a ringing occurs that attracts the attention of passers by and points out jokers. If we take a look at the enameled iron plate at the bottom of the box, we see that, as soon as the ringing ceases, we must shout in the telephone the fire that it is necessary to fight, and repeat this information until a roaring sound is heard, and which signifies that the firemen have started. After following these instructions to the letter, we can leave the apparatus, whose door remains persistently open. There is nothing more simple than all this, even for a child.
When a person breaks the glass he bears at the same time upon a metallic plate that swings upon a horizontal hinge above, and this motion disengages the bolt of the door, which opens through the pressure of three springs. A very simple play of levers frees the alarm bell, which is analogous to that of the old apparatus ; but, at the same instant, this opening of the door sets in motion the automatic transmitter of the indications of the letter of the alarm and of the name by which it is recognized. This transmitter, which is not very complicated, comprises, in the first place, a cam wheel carrying three times upon its circumference, in Morse characters, the indicating letter, and secondly, a motive weight whose card is wound around the axis of the wheel, and causes it to make an entire revolution when the door opens. The play of a lever is controlled by the cams. At rest this lever communicates with the ground through a movable arm and a special spring. Every passage of a cam lifts a tappet and brings the lever in contact with a special screw for a greater or less length of time, according as it is a question of a dot or a dash. The circuit is completed by the earth, and a Morse receiver located at the engine house inscribes a. dot or a dash, and finally the letter (or rather the letter three times) characteristic of the alarm.
At the engine house, at the moment at which the first emission of the current occurs, as a consequence of the opening of the door of the box, a bell is heard to ring to call the foreman. At the same time, through an original mechanism that we cannot describe, the Morse receiver is freed automatically, and inscribes the indicative of the calling alarm. After the triple inscription of the letter A (-), if it is a question of the ap-
paratus of Chateau-des-Rentiers street, the fireman unhooks his telephone, and this movement interrupts the bell of the alarm. The person who is calling knows then that he can signal the fire in the telephone. At this moment a pin fixed upon the cam wheel has lifted the movable arm, made it tilt, and put the telephone in circuit. The fireman inscribes the indications given, and when they are very clear he depresses a special lever, introduces the current of the battery upon the line, and, thanks to an interrupter, the telephone of the alarm renders a sound announcing to the person interested that the firemen are apprised.
All the manceuvres are, therefore, very simple. But the Digeon apparatus has other advantages. It permits notably of keeping the men who have started for the fire in communication with the house, in order to ask for reinforcement, for example. In fact, every alarm is provided at the side with a door that is opened with a special key and exposes a jaw into which are introduced the wires of a movable telephone and a Morse key to effect calls. We must not omit to mention particularly the movable telephone that is employed in this case. It is due to Commandant Krebs, like the one that is arranged in the alarm. It is a question in both cases of a remarkable magnetic transmitter. The vibrating plate is ninetyeight millimetres in diameter in the stationary apparatus and seventy-seven in the movable. For the latter, it is coupled with the Ader receiver mounted through a slide upon the junction rod.
Let us say further that Mr. Digeon has devised a low priced alarm designed for private houses. It is of wood, is fixed against a wall and is wound up through the opening of the door. Besides, the telephone is accompanied with two receivers that permit of communicating with the engine house. These apparatus can be connected gratuitously with the municipal system.
It is opportune at the moment in which Paris is thus improving its fire service, to remark that Brussels, our close-by neighbor, possesses a very remarkable installation of electric alarms. Forty bureaux of communal administration are subscribers to the telephone system. There are fifty automatic electric fire alarms connected with twelve receiving stations. Twenty-one telegraphic stations connect the police offices and stations with the central office, and at the latter there end eighteen telegraph lines coming from the police stations of the seven faubourgs. It is necessary to add to this thirty-seven microphone and eighteen telephone stations putting the services of the external administration in communication with the city hall. It will be understood that these are so many stations capable of serving to send out alarms of fire.