operated by 1 press-button. The arrangement of this is the same
whether the line be long or short. Set up the bell in the required
place, with the gong down or up as may be chosen; fix press-button
where wanted, taking all advantages offered by the plan of the house;
e.g. a wall behind which is a closet is an excellent place to attach
electrical fixtures, because then it is easy to run all the wires
in the closets, and out of sight. Set up the battery in a convenient
place, and, if possible, in an air-tight box. Calculate how much
wire will be requisite, and measure it off, giving a liberal supply;
joints in inside work are very objectionable, and only admissible
where absolutely necessary. Cut off insulation from ends of wire
where contact is to be made to a screw. Only 3 wires are necessary,
i.e. (1) from 1 spring of the press-button to 1 pole of the battery,
say the carbon, (2) from the other spring of the button to 1
binding-screw of the bell, (3) from the other pole of the battery
to the other binding-screw of the bell. In stripping wires, leave
no ragged threads hanging; they get caught in the binding-screw,
and interfere with the connection of the parts. After stripping the
wire sufficiently, make the ends not only clean but bright. Never
run 2 wires under 1 staple. A button-switch should be placed in the
battery-circuit, and close to the battery, so that, to avoid leakage
and accidental short circuiting when the bells are not used for some
time, it may be opened.
(_b_) 1 Bell and 2 Press-buttons.--The next system is an arrangement
of 2 press-buttons in different places to ring the same bell. Having
fixed the bell and battery, and decided upon the position of the
2 buttons, run the wires as follows:--1 long covered wire is run
from 1 pole of the battery to 1 of the springs of the most distant
press-button, and where this long wire approaches nearest to the
other press-button it is stripped for about 1 in. and scraped clean;
another wire, also stripped at its end, is wound carefully around the
bared place, and the joint is covered with kerite tape; the other end
of the piece of wire thus branched on is carried over and fastened
to the spring of the second press-button. This constitutes a battery
wire branching to 1 spring of each press-button. Then run a second
wire from 1 of the bell binding-screws to the other spring of the
most distant press-button, branching it in the same manner as the
battery-wire to the other spring of the second button; connect the
other pole of the battery to the second binding-screw of the bell,
and the arrangement is complete--a continuous battery-circuit through
the bell when either of the buttons is pressed. Before covering the
joints with tape, it is well to solder them, using rosin as a flux.
(_c_) 2 Bells and 1 Press-button.--When it is required to have 2
bells in different places, to ring from 1 press-button at the same
time, after erecting the bells, button, and battery, run a wire from
the carbon pole of the battery and branch it in the manner described
to 1 binding-screw of each bell; run a second wire from the zinc pole
of the battery to 1 spring of the button, and a third wire from the
other spring, branching it to the remaining binding-screw of both
bells. It will not answer to connect 2 or more vibrating bells in
circuit one after another, as the 2 circuit-breakers will not work in
unison; they must always be branched, i.e. a portion of the main wire
must be stripped, and another piece spliced to it, so as to make 2
ends.
(_d_) There are other methods, one of which is, if more than 1 bell
is designed to ring steadily when the button is pressed, to let only
1 of the series be a vibrating bell, and the other single-strokes;
these, if properly set up and adjusted, will continuously ring,
because they are controlled by the rapid make and break of the 1
vibrator.
(_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.
[Illustration: 62. Electro-Magnet.]
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.
[Illustration: 63. Bobbin. 64. Winding Bobbin.]
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.