Part 18

(_e_) Annunciator system.--To connect an indicating annunciator of any number of drops with a common bell, to be operated by press-buttons in different parts of a house, is a handy arrangement, as one drop may be operated from the front door, another from the drawing-room, a third from the dining-room, and so on. The annunciator is fastened up with the bell near it. All the electro-magnets in the annunciator are connected by 1 wire with 1 binding-screw of the bell, and the other binding-screw of the bell is connected with the zinc of the battery. It is a good plan to run a wire through the building from top to bottom, at one end connecting it with the carbon pole of the battery. It ought to be covered with a different coloured cotton from any other, so as to be readily identified as the wire from the carbon. Supposing there are 6 press-buttons, 1 in each room, run a wire from 1 of the springs of each of the press-buttons to the main wire from the carbon pole, and at the point of meeting strip the covering from both the main wire and the ends of the branch wires from the press-buttons, and fasten each branch wire to the main wire, virtually bringing the carbon pole of the battery into every press-button. Next, lead a second wire from the other spring of each press-button to the annunciator screw-post belonging to the special drop desired. This will complete the circuit when any of the press-buttons is pushed; for, as each annunciator magnet is connected on 1 side to its own press-button, and on the other side to the common bell, it follows that when any button is pressed, the line of the current is from the carbon pole of the battery, through the points of the press-button, back to the annunciator, thence through the bell to the zinc pole of the battery; and that, therefore, the right annunciator must drop and the bell must ring. In handsome houses, run the wires under the floor as much as possible, and adopt such colours for wire covering as may be harmonious with the paper and paintings. Also test each wire separately, as soon as the connection is made.

(_f_) Double system.--A system of bells in which the signalling is done both ways, that is, in addition to the annunciator and bell located at one point, to be signalled by pressing the button in each room, a bell is likewise placed in each room, or in a certain room, whereon a return signal may be received--transmitted from a press-button near the annunciator. This is a double system, and involves additional wires. One battery may furnish all the current. Run the main carbon wire through the house, as before, in such a manner as to admit of branch wires being easily attached to it. Run a branch wire from it to the spring of one of the press-buttons, a second wire from the other spring of the same button to the screw-post of the bell in room No. 2, and from the other screw-post of the said bell to the zinc pole of the battery. This completes one circuit. The other is then arranged as follows:--The main carbon, besides being led, as already described, to the spring of the press-button in room No. 1, is continued to one of the binding-screws of the bell in the same room; the other terminal of that bell is carried to one spring of the press-button in room No. 2; the complementary spring of that press-button is then connected by a special and separate wire with the zinc of the battery, and the second circuit is then also completed.

An alternative method is to run branches from the main carbon wire to all the press-buttons, and from the main zinc wire to all the bells, connecting by separate wires the remaining bell terminals with the remaining press-button springs. In the latter plan, more wires are necessary. Although the connections of but one bell either way have been described, every addition must be carried out on the same principle.

When 2 points at some distance from one another, e.g. the house and a stable 100 yd. distant, are to be connected, it is easy to run 1 wire, and use an earth return. If gas or water pipes are in use at both points, no difficulty will be found in accomplishing this. A strap-key will in this case be found advantageous as a substitute for a press-button. The connecting wire at each end is fastened to the stem of the key; the back contact or bridge of the key, against which when at rest the key presses, is connected at each end with one terminal of the bell, the other terminal of each bell being connected by wire with the ground. A sufficient amount of battery is placed at each point, and 1 pole of each battery is connected with the earth, the other pole being attached to the front contact of the strap-key. If impossible to get a ground, the second terminal of both bell and battery at each end must be connected by a return wire.

(_g_) Bell and Telephone.--It is a very easy matter to add telephones to bell-signalling appliances, when constructed as here described. The only additions necessary are a branch or return circuit for the telephones, and a switch operated by hand, whereby the main wire is switched from the bell return wire to the telephone return wire. A very simple plan for a bell-call and telephone line from one room to another, can be made as follows: Apparatus required--2 bells, 2 telephones, 2 3-point switches, 2 strap-keys with back and front contacts, and 1 battery. Run 1 wire from the stem of the key in room No. 1 to the stem of the key in room No. 2. This is the main wire. Fix the bell and 3-point switch below it in each room. Connect the back contact of each key by wire to the lever of the 3-point switch, attach 1 of the points of the switch to 1 of the bell terminals, and the other bell terminal to a return wire. The return wire will now connect the second bell terminal in one room with the second bell in the other room. The other point of the switch in each room is now connected by a wire with 1 binding-screw of a telephone, and the other telephone screw is attached by another wire to the bell return. Connecting 1 pole of the battery also to the return wire, and the other pole to each of the front contacts of the keys, the system is complete. When at rest, each switch is turned on to the bell. To ring the bell in the other room, the key is pressed. The battery circuit is then from battery, front contact of the pressed key, stem of key, main wire, stem of distant key, switch, bell, and through return wire to the other pole of the battery. After bell signals are interchanged, the 3-point switches are transferred to the telephone joint, and conversation can be maintained. (Lockwood.)

_Making an Electric Bell._--The following description applies to 3 sizes--viz. for a 2 in. bell, hereafter called No. 1; 2¾ in., or No. 2; 4 in., or No. 3, which sizes are sufficient for most amateurs’ purposes, and, if properly made, a No. 3 Leclanché cell will ring the largest 2 through over 100 yd. No. 24 (B. W. G.) wire.

The Backboard and Cover.--This may be of any hard wood, by preference teak, oak, or mahogany, and if polished, so much the better; the size required will be--

No. 1, 5½ in. long, 3¾ in. wide, ½ in. thick. No. 2, 7 in. ” 3¾ in. ” ¾ in. ” No. 3, 8½ in. ” 5 in. ” ¾ in. ”

The cover must be deep enough to cover all the work, and reach to within about ¼ in. of the top and sides of back, and allow ⅜ in. to ¾ in. between the edge of bell and cover; the making of this had better be deferred until the bell is nearly complete.

The Electro-Magnet.--This should be of good round iron, and bent into a horse-shoe shape (Fig. 62). The part _a b_ must be quite straight, and not damaged by the forging; the bend should be as flat as possible, so as to make the magnet as short as may be (to save space). When made, the magnet is put into a clear fire, and when red hot, taken out and laid in the ashes to slowly cool; care must be taken not to burn it. Lastly, 2 small holes are drilled in the centre of the ends at _c_, about 1/16 in. deep; drive a piece of brass wire tightly into the holes, and allow the wire to project sufficiently to allow a piece of thin paper between the iron and the table when the iron is standing upon it; this is to prevent the armature adhering to the magnet from residuary magnetism, which always exists more or less. The measurements are--

No. 1 size iron ¼ in., _d_ to _e_ ⅝ in., _a_ to _b_ 1¼ in. No. 2 ” 5/16 in., ” ¾ in., ” 1⅜ in. No. 3 ” 7/16 in., ” ¾ in., ” 1½ in.

The Bobbins or Coils.--These are made by bending thin sheet copper round the part _a b_ of the magnet; the edges at _a_ (Fig. 63) must not quite meet. The thickness of this copper must be such that 4 pieces just equal in thickness the edge of a new threepenny-piece (this is rather an original gauge, but then all can get at the thickness this way). The hole in the brass end _b_ must be just large enough to push on firmly over the copper when on the iron; they must then be set true, and soldered on. The brass for the ends may be about as thick as a sixpence; a 1/16 in. hole must be drilled at _c_, close to the copper. The other measurements are as follows:--

No. 1, diameter ⅜ in., length over all 1⅛ in. No. 2, ” ¾ in., ” 1¼ in. No. 3, ” 1 in., ” 1⅜ in.

The brass ends should be neatly turned true and lacquered.

To fill the Bobbins with Wire.--For this purpose, No 28 wire should be used, which is better if varnished or paraffined. The bobbins should be neatly covered with paper over the copper tube and inside of ends, to prevent any possibility of the wire touching the bobbin itself; the bobbin is best filled by chucking it on a mandrel in the lathe, or a primitive winding apparatus may be made by boring a hole through the sides of a small box, fit a wire crank and wooden axle to this, and push the bobbin on the projecting end--thus (Fig. 64): _a_, crank; _b_, box; _c_, bobbin; _d_, axle. The box may be loaded to keep it steady; on any account do not attempt to wind the wire on by hand--the bobbin must revolve. Leave about 1½ in. of wire projecting outside the hole _d_, in end of bobbin, and wind the wire on carefully and quite evenly, the number of layers being respectively 6, 8, and 10; the last layer must finish at the same end as the first began, and is best fastened off by a silk or thread binding, leaving about a 3 in. piece projecting. Both bobbins must be wound in the same direction, turning the crank from you, and commencing at the end nearest the box. The bobbins must now be firmly pushed on the part _a b_ of the magnet, and the two pieces of wire projecting through the hole _c_ soldered together.

To put the Bell together.--First screw on the bell. This should be supported underneath by a piece of ¼ in. iron tube, long enough to keep the edge of the bell ⅜ to ⅝ in. above the backboard. Cut off the hammer-rod, so that when the head is on it will come nearly as low as the bell screw, and in a line with it. Make a hole in the backboard, and drive the armature post in tightly--it must be driven in so far that when the magnet is laid upon the backboard, the centre of the magnet iron and the armature are the same height. Place the magnet so that when the armature is pressed against it, the hammer-head all but touches the bell; screw it into its place by a wooden bridge across the screw passing between the bobbins. By afterwards easing this screw, any little adjustment can be made. The armature spring should tend to throw the hammer-head about ⅝ in. from the bell. The contact-post should be so placed that when the armature touches the magnet, there is a slight space between the platinum point on the screw and the platinum on the spring. In putting in the posts, a piece of copper wire must be driven in with them to attach the wire to. One post can be moved round a little either way to alter the tension of the spring; the screw in the other post can be turned in or out, to just allow the proper break to take place. By screwing it in and out, the ear will soon judge where the bell rings best. (Volk.)

Those desiring further information on batteries, telephones, and all electrical matters, are referred to the Third Series of ‘Workshop Receipts,’ where diffuse instructions are given.

=Thieves and Fire.=--It would be difficult to name two subjects demanding more attention and forethought from the housewife than the means to be adopted for protecting her household from the incursions of thieves and the horrors of fire. Some years ago, the well-known inventor of Chubb’s locks published a little book on these topics, from which we have taken the liberty of condensing a few paragraphs which are full of import to the safety of the dwelling and its inmates.

First with regard to thieves. Chubb remarks that most of the house-robberies so common in all large towns are effected through the common street-door latches in ordinary use being opened by false keys. It is a notorious fact that thousands are made year after year, but which do not afford the least security, as they are all so made that any one key will open the whole. Burglars are sometimes assisted by dishonest servants, but are more often unaided in this way. Frequently some coal-cellar window is left conveniently unbarred, although all other windows and doors are barred and bolted; or perhaps all the windows have safety-fasteners but one, which, of course, will be the one used by the burglars. Beggars or hawkers are often in the pay of thieves, endeavouring to get information--that may not be used perhaps for a long time; and such visitors should never be allowed inside one’s house, though their visits are too often encouraged by the weakness of the domestics.

The remedies best adapted to prevent robbery in these various ways are:--(1) Be careful to have trustworthy servants, or all other precautions are unavailing. (2) Have plate-glass to all windows in the house, for this cannot be broken, as common sheet-glass can, without noise. (3) As shutters are really no protection at all, and frequently are not fastened at night, let all windows and openings that can be reached easily from the ground have strong bars built into the stone or brickwork, not more than 5 in. apart, where this can be done without disfigurement; and let the windows on every upper floor have either Hopkinson’s or Dawes’s patent window fasteners, which cannot be opened from the outside, and are simple and strong in construction and cheap in price. (4) Keep a dog, however small, _inside_ the house; this is a wonderful safeguard, and extremely disliked by burglars. (5) Have any number of bells on shutters, electric wires, or other gimcracks that you please, and place no reliance on any of them. (6) Never allow a stranger to wait inside the door. (7) Leave as little property as possible, certainly no silver plate or jewellery, lying about, so that if a thief should overcome all obstacles to entrance, he may not find much ready to hand.

Precautions against fire are of still greater importance. A few of the commonest causes of fire are guarded against by observing the following simple rules:--(1) Keep all matches in metal boxes, and out of the reach of children; wax matches are particularly dangerous, and should be kept out of the way of rats and mice. (2) Be careful in making fires with shavings and other light kindling. (3) Do not deposit coal or wood ashes in a wooden vessel, and be sure burning cinders are extinguished before they are deposited. (4) Never put firewood upon the stove to dry, and never put ashes or a light under a staircase. (5) Fill fluid or spirit lamps only by daylight, and never near a fire or light. (6) Do not leave a candle burning on a bureau or a chest. (7) Always be cautious in extinguishing matches and other lighters before throwing them away. (8) Never throw a cigar-stump upon the floor or spitbox containing sawdust or trash without being certain that it contains no fire. (9) After blowing out a candle never put it away on a shelf, or anywhere else, until sure that the snuff has gone entirely out. (10) A lighted candle ought not to be stuck up against a frame-wall, or placed upon any portion of the woodwork in a stable, manufactory, shop, or any other place. (11) Never enter a barn or stable at night with an uncovered light. (12) Never take an open light to examine a gas-meter. (13) Do not put gas or other lights near curtains. (14) Never take a light into a closet. (15) Do not read in bed, either by candle or lamp light. (16) The principal register of a furnace should always be fastened open. (17) Stove-pipes should be at least 4 in. from woodwork, and well guarded by tin or zinc. (18) Rags ought never to be stuffed into stove-pipe holes. (19) Openings in chimney-flues for stove-pipes which are not used ought always to be securely protected by metallic coverings. (20) Never close up a place of business in the evening without looking well to the extinguishing of lights, and the proper security of the fires. (21) When retiring to bed at night always see that there is no danger from your fires.

A few other unsuspected causes of fire may be mentioned. A common habit with some people, when ironing, is to rub the hot iron clean with a piece of stuff, paper, or “anything” at hand, and then throw the same aside without further thought. The small piece of stuff, usually more or less scorched, may lie smouldering for hours unsuspected in some corner, especially if shut up in a cupboard or drawer. The danger here alluded to applies equally to the careless throwing aside of anything likely to smoulder, such as cloths caught up at random for holding hot baking tins, kitchener handles, &c. No room ought ever to be left unoccupied without a guard being placed on the fire. Most of us have had experience of sudden small explosions of the coals, and holes being burnt in the hearthrug, even when there is some one at hand to stamp out the fire at once; and we can imagine what the consequences would be if the hearthrug had been left to smoulder. In the case of steam-pipes, after wood has remained a long time in contact with steam, hot-water, or hot-air pipes, the surface becomes carbonised. During the warm season, the charcoal absorbs moisture. When again heated, the moisture is driven off, leaving a vacuum, into which the fresh air current circulating around the pipes rapidly penetrates, and imparts its oxygen to the charcoal, causing a gradual heating and eventually combustion. The rusting of the pipes contributes also to this result, inasmuch as the rust formed during the hot season may be reduced by the heat of the pipes to a condition in which it will absorb oxygen to the point of red heat.

With respect to the detection of fires there is very little to say; but every one should acquaint themselves with the best means of getting from the house in case of fire cutting off the usual exit. At such a critical moment, when, perhaps aroused from a sound sleep, one finds oneself in a house on fire, presence of mind is the first thing required, yet a few simple suggestions that will start to the memory may be of value. If, on the first discovery of the fire, it is found to be confined to one room, and to have made but little progress, it is of the utmost importance to shut, and keep shut, all doors and windows. If the fire appears at all serious, and there are fire-engines at a reasonable distance, it is best to await their arrival, as many buildings have been lost from opening the doors and attempting to extinguish fires with inadequate means. If no engines are within reach, and you have not a hand-pump or an extincteur, the next best thing is to collect as many buckets outside the room on fire as can be obtained, keeping the door shut while more water is being collected. A rough-and-ready protection from breathing smoke may be had by thoroughly wetting a towel and fastening it firmly round the face over the mouth and nostrils. But if the flames have too great a hold to allow of escape by the staircase or roof, and the window of the room is the only means of egress, the situation becomes serious, unless its possibility has been foreseen and guarded against.

Only as _the last_ resource should a person run the risk of jumping to the ground; either endeavour by tying the bedclothes together to make some sort of rope, fastening one end to a heavy piece of furniture, and going down the rope hand-over-hand--a rather difficult thing to do without practice--or, if within reach of one, wait as long as possible for the arrival of a fire-escape or ladder. Some people always keep a stout knotted rope in their room, and have an iron hook fixed inside the window, to which it may be attached. Merryweather and Sons, 63 Long Acre, London, make domestic fire-escapes which admit of even women and children lowering themselves from windows. As to means of escape available from the outside for high houses, there are many obvious plans which might be adopted, but among these there are two which appear to be specially easy of attainment, and within the reach of all concerned, at a moderate cost. The first is to fix on buildings external ladders of wrought iron or some other material able to resist the effects of fire at its commencement, and extending from the roof to within 40 ft. of the ground; the other, to provide on every story continuous balconies of wrought iron or any other material proof against immediate destruction by heat; and if the balconies on the several stories were made to communicate with each other by means of external stairs, great additional safety would be attained.

The Royal Society for the Protection of Life from Fire has published the following directions for saving life at fires. See also p. 1002.

_For Bystanders._--1. Immediately on the fire being discovered give an alarm to the nearest fire-escape station, not delaying an instant; do not wait to see if it is wanted. Life is more precious than property, and events have too often proved how fatal even a moment’s hesitation is in sending for the fire-escape. It is the fire-escape man’s duty to proceed to the place of alarm immediately.

2. In the absence of a fire-escape, or pending its arrival, ladders and ropes should be sought for. Two constables or other qualified persons should ascend to the roof through the adjoining houses. The most efficient assistance can sometimes be rendered by an entrance to the upper part of the house on fire, either by the attic windows, the loft-door, or by removing the tiles; or sometimes the aid of one end of a rope (knotted) might be afforded from the adjoining window, which, being passed by the person in danger round some article in the room, he could lower himself or others into the street, and the other end of the rope being controlled of course by those rendering the aid from the adjoining house. A short ladder can often be made available at the second or perhaps the third, floor of houses built with a balcony or portico, by the constable or other person first ascending to the balcony, and then placing the ladder thereon, reach the rooms above.

3. In a narrow street or court assistance may be given from the windows of the opposite house, particularly by a ladder placed across the street from window to window.

4. When no other means present themselves the bystanders had better collect bedding at hand, in case the inmates throw themselves from the windows. A blanket or carpet held stretched out by several persons will serve the purpose. The Metropolitan Fire Escape Brigade carry jumping-sheets with them for use upon emergency.