CUTTING DOWN EXPENSE.
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.