If the cost appears prohibitive, it may be reduced somewhat (1) by
using thinner boards; (2) by reducing the height of the shed by 1 foot.
A very cheap shed, but of course not comparable in quality with the one
described, can be made by using odd rough boards for the outside, and
covering them with roofing felt well tarred.
VIII.
A TARGET APPARATUS FOR RIFLE SHOOTING.
The base is a 1-inch board, 18 inches long and 7 inches wide.
The target-holder is a piece of wood 1-1/2 inches square, and a couple
of inches longer than the side of the largest target to be used. To one
face nail a piece of strip lead as weight; and to the parallel face
attach, by means of brads driven in near one edge, a piece of thin wood
of the same size as the face. The free long edge of this should be
chamfered off slightly on the inside to enable the target to be slipped
easily between it and the roller.
The roller is pivoted on two short spindles—which can be made out of
stout wire nails—driven into the ends near the face farthest from the
weight. (See Fig. 26.)
For standards use a couple of the small angle irons used for supporting
shelves, and sold at about a penny each. These are screwed on to the
board 2 inches from what may be considered to be the rear edge, and are
so spaced as to leave room for a washer on each spindle between the
roller and the standards, to diminish friction.
[Illustration: FIG. 26.-Side elevation of disappearing target
apparatus.]
Remove one standard, and drive into the roller a piece of stout wire
with its end bent to form an eye. The inclination of the arm to the
roller is shown in Fig. 26.
To the front of the board now nail a rectangle of stout sheet iron,
long and deep enough to just protect the standards and roller. Place
the roller in position, insert a target, and revolve the roller to
bring the target vertical. A small wire stop should now be fixed into
the baseboard to prevent the arm coming farther forward, and a hole for
the operating string be drilled in the protection plate at the
elevation of the eye on the arm. The edges of this hole need careful
smoothing off to prevent fraying of the string. A small eyelet or brass
ring soldered into or round the hole will ensure immunity from chafing.
Drive a couple of long wire nails into the front edge of the board
outside the iron screen to wind the string on when the target is put
away.
It may prove a convenience if plain marks are made on the string at the
distances from which shooting will be done.
The above description covers apparatus for working two or more targets
simultaneously on a long roller, or separately on separate rollers
mounted on a common baseboard.
If it is desired to combine with the apparatus a “stop” for the
bullets, the latter (a sheet of stout iron of the requisite strength)
may be affixed to the rear of the baseboard, and furnished with a
handle at the top to facilitate transport.
IX.
CABINET-MAKING.
A Match-box Cabinet.
This is useful for the storage of small articles, such as stamps, pens,
seeds, needles, and a number of other minor things which easily go
astray if put in a drawer with larger objects.
The best boxes for the purpose are those used for the larger Bryant and
May matches. Select only those boxes of which the tray moves easily in
the case.
The cases should be stood on end on some flat surface while being glued
together. A box or drawer with truly square corners is useful for
assembling them in; if they are packed into one corner they cannot slew
about. Press the boxes together while the glue is setting.
Now glue the back ends of the cases (from which the trays should have
been removed), and press them against a piece of thin card. When the
glue is dry, apply some more with a small brush to the back angles
inside the covers, to ensure a good hold on the backing. Trim off the
card to the outline of the pile.
[Illustration: FIG. 27.—Match-box cabinet.]
Select for the front end of the drawer that for which the wood is
doubled over. Paste outside the end a piece of white paper, whereon
words and numbers will be more plainly visible. The life of the trays
will be increased if the insides are neatly lined with thin paper.
For “handles” use boot buttons, or loops of thin brass wire, or brass
paper clips. To give the cabinet a neat appearance you should cover it
outside with paper of some neutral tint; and if you wish it to be
stable and not upset when a rather sticky drawer is pulled out, glue it
down to a solid wooden base of the proper size.
A Cardboard Cabinet.
We now proceed to a more ambitious undertaking—the manufacture of a
cabinet for the storage of note-paper, envelopes, labels, etc. The only
materials needed are some cardboard and glue; the tools, a ruler and a
very sharp knife. For the marking out a drawing board and T-square are
invaluable. The cardboard should be fairly stout, not less than 1/16
inch thick.
Begin with the drawers; it is easier to make the case fit the drawers
than vice versa.
Mark out the drawers as shown in Fig. 28. The areas AA are the front
and back; BB the sides. The dotted lines indicate the lines along which
the cardboard is bent up. The sides are of exactly the same length as
the bottom, but the front and back are longer than the bottom by twice
the thickness of the cardboard, so as to overlap the sides. (The extra
length is indicated by the heavy black lines.)
[Illustration: FIG. 28.—Drawer of cardboard cabinet marked ready for
cutting.]
Measure and cut out very carefully to ensure all the drawers being of
the same size. Lay a piece of card under the thing cut to avoid
blunting the knife or damaging the table. When the blanks are ready,
cut them almost through along the dotted lines. Use several strokes,
and after each stroke test the stubbornness of the bend. When the card
is almost severed it will bend up quite easily. Note.—Bend as shown in
the inset C; not the other way, or you will snap the card. If you
should be so unlucky as to cut the card through in places, paste a
strip of thin paper along the line before turning up.
The four flaps are now bent up, glued together, and covered outside
with paper. This part of the business is easy enough if a small
square-cornered wooden box be used as a support inside at each angle in
turn. It is advisable to glue strips along all the bends both inside
and outside. The external strips should be flattened down well, so as
to offer no loose edges.
Compare the drawers, and if one is slightly wider than the rest, use it
to guide you in making the measurements for the case.
The sides and back of the case are cut out of a single piece. The sides
should be a quarter of an inch deeper than the drawers to allow some
overlap; the back slightly wider than the drawer.
As each drawer will be separated from that above it by a shelf,
allowance must be made for the shelves, and also for a twentieth of an
inch or so of “play” to each drawer. To keep on the safe side leave a
little extra stuff to be removed later on.
Cut out the bottom to fit inside the back and sides exactly, and a
sufficient number of shelves of precisely the same size as the bottom.
Attach the bottom to the sides and back with internal and external
strips. When the glue has set, place the guide drawer in position, and
lay on it a piece of thin card to cover it over. This card is merely a
removable “spacer.” Along the side and back edges of the shelf stick
projecting strips of stout paper. When the adhesive is dry, turn the
strips round the end at right angles to the division, glue them
outside, and lay the division in position on top of the “spacer.”
Place the second drawer and shelf in like manner, and continue till the
top of the cabinet is reached. Then mark off and cut away any
superfluous card. Glue the top edges, and stand the cabinet head
downwards on a piece of cardboard. Trim off the edges of this, and the
top is completed, except for binding the corners.
Then attend to the outside back corners of the case, and paste strips
in the angles under the shelves. The strips should be forced well into
the angles.
For handles use brass rings let sufficiently far through the fronts of
the drawers for a wedge of card to be slipped through them and stuck in
position. The appearance of the cabinet will be enhanced by a neatly
applied covering of paper.
A Cigar-box Cabinet.
At the rate of a halfpenny or less apiece one may buy the cigar boxes
made to hold twenty-five cigars. These boxes, being fashioned by
machinery, are all—at any rate all those devoted to a particular
“brand”—of the same dimensions; they are neatly constructed, and their
wood is well seasoned. Anyone who wishes to make a useful little
cabinet may well employ the boxes as drawers in the said cabinet (Fig.
29).
Each box should be prepared as follows:-Remove the lid and paper
lining, and rub all the paper binding off the outside angles with a
piece of coarse glass paper. This is a safer method than soaking-off,
which may cause warping and swelling of the wood. Then plane down the
tops of the two sides till they are flush with the back and front, and
glue into the corners small pieces of wood of right-angled-triangle
section to hold the sides together and the bottom to the sides. To
secure the parts further cut a number of large pins down to 3/4 inch,
and drive these into the sides through holes carefully drilled in the
bottom. Finally, rub the outside of the drawer well with fine glass
paper or emery cloth till the surface is smooth all over.
The Case.—If mahogany can be obtained for this, so much the better, as
the wood will match the boxes. In default of it, a white wood, stained,
will have to serve.
[Illustration: FIG. 29.—Cabinet with cigar-box drawers.]
The two sides of the case should be prepared first Wood 3/8 inch thick
is advised. Each side is 1 inch wider than the depth (outside) of a
drawer from front to back. (Whether the drawers shall slide in
lengthways or flatways is for the maker to decide.) The length of a
side is calculated on the basis that the drawers will be separated from
one another by runners 1/4 to 5/16 inch deep, and that a slight
clearance must be allowed for the drawers to slide in and out freely.
In the first instance cut the sides a bit too long. If it be preferred
to insert the bottom between the sides, the length must be increased
accordingly.
The runners are cut out of the box lids, and planed till their top and
bottom edges are parallel. Their length is 1/4 inch less than the depth
of a drawer. To fill up the spaces between the drawers in front you
will need some slips of the same depth as the runners, and 3/8 inch
longer than the drawer, so that they may be let 3/16 inch into the
sides of the case at each end.
Affixing the Runners.—This is a very easy matter if a wooden spacer,
slightly wider than the depth of the drawer, is prepared. Having
decided which is to be the inside face and the forward edge of a side,
lay the side flat, and apply the spacer with one edge flush with the
bottom of the side, or as far away from it as the thickness of the
bottom, as the case may be, and fix it lightly in position with a
couple of tacks. The first runner is laid touching the spacer and a
little back from the edge to give room for the cross-bar, and fastened
by means of short tacks, for which holes had better be drilled in the
runner to prevent splitting. The spacer is now transferred to the other
side of the runner, and the second runner is fastened on above it; and
so on till all the runners are in position. The square should be used
occasionally to make sure that the tops of the runners are parallel to
one another. The other side having been treated in like manner, any
spare wood at the top is sawn off.
The notches for the front cross-bars between drawers are cut out with a
very sharp narrow chisel.
The Top and Bottom.—Make the top of the same thickness as the sides;
the bottom of somewhat stouter wood. If the bottom is cut a bit longer
than the width of the case, and neatly bevelled off, it will help to
smarten the appearance of the cabinet.
When fixing the sides to the bottom and top get the distance correct by
placing the top and bottom drawers in position, and insert a piece of
thin card between one end of the drawer and the side. This will ensure
the necessary clearance being allowed for.
The Back.—Cut this out of thin wood. The top of a sweetstuff
box-costing about a halfpenny—will do well enough. It should be quite
rectangular and make a close fit, as it plays the important part of
keeping the case square laterally. Bevel its back edges off a bit. Push
it in against the back ends of the runners, and fix it by picture brads
driven in behind.
The front bars should now be cut to a good fit and glued in the
notches.
This completes the construction.
Drop handles for the drawers may be made out of semicircles of brass
wire with the ends turned up. The handles are held up to the drawer by
loops of finer wire passed through the front and clinched inside.
The finishing of the outside must be left to the maker’s taste.
Varnishing, or polishing with warmed beeswax, will add to the general
appearance, and keep out damp.
The total cost of a ten-drawer cabinet ought not to exceed eighteen
pence.
A Tool Cabinet.
The wooden cabinet shown in Fig. 30 is constructed, as regards its
case, in the same way as that just described, but the drawers are built
up of several pieces. The over-all dimensions of the cabinet
represented are as follows: Height, including plinth, 25 inches; width,
17-3/8 inches; depth, 10-1/2 inches. The drawers are 16 inches wide
(outside), by 10-1/8 inches from back to front, and, reckoning from the
bottom upwards, are 3-1/4, 3, 2-1/2, 2, 2, 2, 2, and 1-3/4 inches deep.
[Illustration: FIG. 30.—Large cabinet (a), details of drawer joints (b,
c, d), and padlock fastening (e).]
The construction of the drawers is indicated by the diagrams, Fig. 30,
b, c, d. The fronts are of 5/8-inch, the sides and backs of 3/8-inch,
and the bottoms of (barely) 1/4-inch wood. The grooves should not come
nearer than 1/8-inch to the bottom edge, or be more than 5/16 inch wide
and deep. The possessor of a suitable “plough” plane will have no
difficulty in cutting them out; in the absence or such a tool the
cutting gauge and chisel must be used.
The back piece of a drawer has 1/4-inch less height than the front, to
allow the bottom to be introduced. The ends or the bottom are bevelled
off towards the top edge to fit the grooves, so that no part may be
above the grooves.
Glue should be used to attach the sides of a drawer to the back and
front in the first place, and nails be added when the glue has set. As
an aid to obtaining perfect squareness, without which the drawers will
fit badly, it is advisable to mark out on a board a rectangle having
the exact inside dimensions of a drawer, and to nail strips of wood up
to the lines on the inside. If the parts are put together round this
template they will necessarily fit squarely.
Divisions.—If the drawers are to be subdivided in one direction only,
the partitions should run preferably from back to front, as this
enables the contents of a compartment to be more easily seen. Where
two-direction division is needed the partitions are cut as shown in
Fig. 31. All partitions should touch the bottom, and be made immovable
by gluing or nailing. It is a mistake to have so many divisions in a
drawer that the fingers cannot get into them easily.
Wooden knobs for the drawers can be bought very cheaply of any turner,
or suitable brass knobs at any ironmonger’s. Take care that the knobs
are in line with one another; otherwise the general appearance of the
cabinet will suffer.
[Illustration: FIG. 31.—Divisions of drawer notched to cross each
other.]
Lock and Key.—If a cabinet is intended for storage of articles of any
value it should be provided with lock and key. One lock will secure all
the drawers if attached to a flap hinged on one side to the cabinet, as
shown in Fig. 30 a, to engage a catch projecting from one of the
drawers. A special form of lock is sold for the purpose. If the single
flap seems to give a lop-sided effect, place a fellow on the other
side, and fit it with sunk bolts to shoot into the overhanging top and
plinth. If you wish to avoid the expense and trouble of fitting a lock,
substitute a padlock and a staple clinched through the front of a
drawer and passing through a slot in the flap (Fig. 30, e).
Alternative Method.—The fixing of the front bars can be avoided if the
front of each drawer (except the lowest) be made to overhang the bottom
by the depth of the runner. This method, of course, makes it impossible
to stand a drawer level on a level surface.
X.
TELEGRAPHIC APPARATUS.
The easily made but practical apparatus described in this chapter
supplies an incentive for learning the Morse telegraphic code, which is
used for sending sound signals, and for visible signals transmitted by
means of flags, lamps, and heliograph mirrors. Signalling is so
interesting, and on occasion can be so useful, that no apology is
needed for introducing signalling apparatus into this book.
The apparatus in question is a double-instrument outfit, which enables
an operator at either end of the line to cause a “buzzer” or “tapper”
to work at the other end when he depresses a key and closes an electric
circuit. Each unit consists of three main parts—(1) the transmitting
key; (2) the receiving buzzer or tapper; (3) the electric battery.
The principles of an installation are shown in Fig. 33. One unit only
is illustrated, but, as the other is an exact duplicate, the working of
the system will be followed easily.
[Illustration: Fig. 32.—Morse alphabet]
A wooden lever, L, is pivoted on a support, A. Passing through it at
the forward end is a metal bar having at the top a knob, K, which can
be grasped conveniently in the fingers; at the other a brass screw, O,
which is normally pulled down against the contact, N, by the spiral
spring, S. The contact M under K is in connection with the binding post
T1 and N with binding post T3; K is joined up to T2, and O to T4.
T3 and T4 are connected with one of the line wires; T1 with the other
wire through a battery, B; T3 with the other wire through the buzzer,
R. [1]
[Footnote 1: For the buzzer may be substituted the tapper, described on
a later page.]
Assuming both keys to be at rest, as in Fig. 33, the two buzzers are
evidently in circuit with the line wires, though no current is passing.
If the stem of K is depressed to make contact with M, the electric
circuit of which the battery, B, forms part is completed, and the
buzzer at the other end of the lines comes into action. Since the
depression of K raises O off N, the “home” buzzer’s connection with the
line wires is broken, to prevent the current being short-circuited. The
fact that this buzzer is periodically in circuit, even when the key is
being worked, makes it possible for the operator at the other end to
attract attention by depressing his key, if he cannot read the signals
sent.
[Illustration: Fig.33—Telegraphic apparatus; sending key, buzzer and
battery]
Making the Keys.
Transmitting keys can be bought cheaply, but not so cheaply as they can
be made. The only expense entailed in home manufacture is that of the
screw terminals for connecting the keys with the lines and buzzers.
These cost only a penny each, and, if strict economy is the order of
the day, can be dispensed with should the apparatus not have to be
disconnected frequently.
The size of the key is immaterial. The keys made by me have levers 1
inch wide and 5-1/2 inches long, oak being chosen as material, on
account of its toughness. K is in each case a small wooden knob on a
piece of 3/16-inch brass rod; O a 1-1/2-inch brass screw; A a piece of
sheet brass 3-1/2 inches long, marked off carefully, drilled 1/8 inch
from the centre of each end for the pivot screws, and in four places
for the holding-down screws, and bent up at the ends to form two
standards. If you do not possess any brass strip, the lever may be
supported on wooden uprights glued and screwed to the base.
[Illustration: Fig. 34—Telegraphic apparatus mounted on baseboard]
Contact M is a small piece of brass attached to the base by a screw at
one end and by T1 at the other. K was drilled near the end to take the
short coil of insulated wire joining it to T2, and O was similarly
connected with T4.
The spring, S, should be fairly strong. A steel spiral with a loop at
each end is most easily fitted. Drill holes in the lever and base large
enough for the spring to pass through freely, make a small cross hole
through the lever hole for a pin, and cut a slot across the base hole
for a pin to hold the bottom of the spring. Adjust the lever by means
of screw O so that there is a space of about 1/4-inch between K and M
when O and N are in contact, and after the spring has been put in
position give the screw a turn or two to bring K down to within 1/16
inch of M. This will put the required tension on the spring.
The Buzzers.—For these I selected a couple of small electric bells,
costing 2s. 6d. each. Their normal rate of vibration being much too
slow for telegraphic purposes, I cut off the hammers to reduce the
inertia, and so adjusted the contact screw that the armature had to
move less than one hundredth of an inch to break the circuit. This
gave so high a rate of vibration that the key could not make and break
the circuit quickly enough to prevent the buzzer sounding.
A Morse Tapper or Sounder.
In postal telegraph offices a “sounder,” and not a “buzzer,” is
generally used to communicate the signals. Instead of a continuous
noise, lasting as long as the key at the transmitting station is held
down, the operator at the receiving station hears only a series of taps
made by an instrument called a “sounder.” The principle of this simple
device is illustrated by the working diagrams in Fig. 35. M is a
horseshoe magnet fixed to a base, A. Close to it is an armature, AR, of
soft iron, attached to a lever, L, which works on a pivot and is held
up against a regulating screw, P1, by the pull of the spring SP. When
current passes through the magnet the armature is attracted, and the
point of the screw S2 strikes against P2; while the breaking of the
circuit causes L to fly back against S1. The time intervening between
the “down” and “up” clicks tells the operator whether a long or a
short—dash or a dot—is being signalled.
[Illustration: FIG. 35.-Elevation and plan of telegraphic sounder.]
Materials.—A horseshoe magnet and armature taken from an electric bell
provide the most essential parts of our home-made instrument in a cheap
form. If these are available, expense will be limited to a few pence.
Oak or walnut are the best woods to use for the lever, being more
resonant than the softer woods, and for the standard B and stop V. Any
common wood is good enough for the base A.
The lever L is 6 inches long, 1/2 inch deep, and 3/8-inch wide, and is
pivoted at a point 4-1/4 inches from the stop end. The hole should be
bored through it as squarely as possible, so that it may lie centrally
without B being out of the square. A piece of metal is screwed to its
top face under the adjusting screw S1.
The spring is attached to L and A in the manner already described on p.
89 in connection with the “buzzer.”
The plate P2 should be stout enough not to spring under the impact of
the lever. Fig. 36 is an end view of the standard B. The drilling of
the pivot hole through this requires care. The screw S2 should be so
adjusted as to prevent the armature actually touching the cores of the
magnets when attracted. The ends of the magnet winding wire, after
being scraped, are clipped tightly against the base by the binding
posts T1 T2.
If sounders are used in place of buzzers they are connected up with the
keys, batteries, and line wires in the manner shown in Fig. 33.
Batteries.
The dry cells used for electric bells are the most convenient batteries
to use. They can now be purchased at all prices from a shilling
upwards, and give about 1-1/2 volts when in good condition. One cell at
each end will suffice for short distances, or for considerable
distances if large conductors are used. If a single cell fails to work
the buzzer strongly through the circuit, another cell must be added.
[Illustration: FIG. 36.—Standard for sounder.]
For ease in transport it will be found advisable to mount key, buzzer,
and battery on a common baseboard, which should be provided with a
cover and handle. The three parts are interconnected with one another,
and the line wire terminals as sketched in Fig. 34. This arrangement
makes the apparatus very compact and self-contained. As a finishing
touch fit the lid inside with clips for holding a stiff-backed writing
pad and pencil for the recording of messages.
Lines.—Fencing made of stout galvanized iron wires strung on wooden
posts supplies excellent conductors for practice purposes, provided the
posts be quite dry. In wet weather there will be leakage. (Fencing with
metal posts is, of course, unsuitable, as every post short-circuits the
current.) The two wires selected for land lines must be scraped quite
bright at the points where the connections are to be made.
It is an easy matter to rig up a telegraph line of galvanized wire 1/12
to 1/8 inch in diameter, strung along insulators (the necks of bottles
serve the purpose excellently) supported on trees, posts, or rough
poles. The length of the line will be limited by the battery power
available, but a 6-volt battery at each end will probably suffice for
all experimental purposes. A second wire is not needed if one terminal
at each end is connected with a copper plate sunk in the ground, or
with a metal fence, drain-pipe, etc.
XI.
A RECIPROCATING ELECTRIC MOTOR.
The electric motor to be treated in this chapter illustrates very
prettily the attractive force of a hollow, wire-wound bobbin on a
movable core, when the electric current is passed through the wire. If
one inserts the end of an iron rod into the coil, the coil exerts a
pull upon it, and this pull will cease only when the centre of the rod
is opposite the centre of the coil. This principle is used in the
“electric gun,” which in its simplest form is merely a series of
powerful coils arranged one behind another on a tube through which an
iron or steel projectile can pass. The projectile closes automatically
the circuit of each coil in turn just before reaching it, and breaks it
before its centre is halfway through the coil, being thus passed along
from one coil to the other with increasing velocity.
Our motor is essentially a very inefficient one, its energy being small
for the current used, as compared with a revolving motor of the usual
kind. But it has the advantage of being very easy to make.
[Illustration: FIG. 37.—Electric reciprocating engine and battery.]
How it works.—The experimental engine, constructed in less than a
couple of hours, which appears in Fig. 38, consists of a coil, C,
strapped down by a piece of tin to a wooden bedplate; a moving plunger,
P, mounted on a knitting-needle slide rod, SR; a wire connecting rod,
SR; a wooden crank, K; and a piece of knitting-needle for crank shaft,
on which are mounted a small eccentric brass wipe, W, and a copper
collar, D. Against D presses a brass brush, B1 connected with the
binding post, T1; while under W is a long strip of springy brass
against which W presses during part of every revolution. T2 is
connected to one end of the coil winding, and T1 through a 4-volt
accumulator or three dry cells, with the other end of the coil. When W
touches B2 the circuit is completed, and the coil draws in the plunger,
the contact being broken before the plunger gets home. The crank
rotates at a very high speed if there is plenty of battery power, all
the moving parts appearing mere blurs.