Things To Make, Archibald Williams [great book club books .txt] 📗

3. The ratio 1:3 is the easiest to begin upon, so the experimenter's first efforts may be directed to it. He should watch the growth of the figure closely, and note whether the repeat line is made in front of or behind the previous line of the same loop. In the first case the figure is too flat, and the weight of the upper pendulum must be raised; in the second case the weight must be lowered. Immediately an exact harmonic is found, the position of the weight should be recorded.

Interesting effects are obtained by removing the lower pendulum and allowing the apparatus to describe two elliptical figures successively, one on the top of the other, on the same card. The crossing of the lines gives a "watered silk" appearance to the design, which, if the pen is a very fine one and the lines very close together, is in many cases very beautiful.

Readers who wish for further information on this fascinating subject are recommended to purchase "Harmonic Vibrations," published by Messrs. Newton and Co., 72 Wigmore Street, London, W. This book, to which I am much indebted, contains, besides much practical instruction, a number of charming reproductions of harmonograms.

Before closing this chapter I should like to acknowledge the kind assistance given me by Mr. C. E. Benham, who has made a long and careful study of the harmonograph.

This useful little article can be constructed in a couple of hours by a handy person. In general idea it consists of a diamond-shaped box to hold vestas, working up and down diagonally on a vertical member (A in Fig. 179 (1)), which passes through slits at the top and bottom, and runs in grooves cut in the sides of the box. The top of A is grooved to allow a match to rest on it. When the box is drawn up to the full extent allowed by a transverse pin in the slot shown in Fig. 179 (2), the groove is at the lowest point of the box, and is covered by the matches. When the box is lowered, A catches a vesta and takes it up through the top, as seen in Fig. 178, for removal by the fingers.

The only materials required are a cigar-box, some pins, and a supply of glue. The box should be carefully taken to pieces, and the parts soaked in hot water till freed of all paper, and then allowed to dry under pressure, small slips of wood being interposed across the grain to keep them separate and permit the passage of air.

[Illustration: FIG. 178.—Self-supplying matchbox, with match in position for removal by fingers.]

When the wood is dry, cut out with a fret saw two pieces shaped like Fig. 179 (3), to form the ends of the box. Allow a little surplus, so that the edges may be finished off neatly with chisel and plane. The two ends should match exactly, or there will be trouble at a later stage.

Now cut, down the centre of each a groove for one edge of A to run in. By preference it should be square; but if you do not possess the necessary chisel, a V groove made with a knife will suffice—and, of course, in this case the edges of A will have to be bevelled to fit.

[Illustration: FIG. 179.—Details of self suplying matchbox.]

The four sides of the box, BB and CC, are next cut out. Their sectional shape is shown in Fig. 179 (1). They should be rather longer than the length of the ordinary vesta, and all of exactly the same length, and rectangular. A very small hack saw (costing about 1s.) with fine teeth is the best possible tool for close cutting, and a small 1 shilling iron plane is invaluable for truing and bevelling the edges.

The glue pot, which we will assume to be ready for use, is now needed to attach the fixed B (the other B is hinged to form a lid for filling the box through) and CC to the ends. This operation must be carried out accurately, so that the slots may not be blocked.

While the glue is setting, cut out A, allowing an extra 1/16 inch of width for fitting. The slot down the centre is best made with a fret saw, and should be smoothed internally by drawing a strip of fine glass paper to and fro through it. The length of the slot is of great importance. It must reach to just that distance from the top edge which brings that edge flush with the bottom of the box when the box is raised; and in the other direction must permit the box to settle on to its foot, so that the match lifted shall project above the box.

Work the edges of A down carefully (double-bevelling them if the notches are V-shaped) till A will run easily, but not loosely, in the box. Then cut out two slips, DD, and bevel them at the top to an angle of 45 degrees. Put A in place and glue them on, taking care that the glue does not hold them fast to A.

Pierce a small hole through DD, in line with the slot, and insert a pin.
Draw the box fully up, and see if the top of A sinks to the proper place.
If it projects a little, lengthen the slot a trifle.

Cut out the supports EE, finish them neatly, and glue them to A. Make sure that the pin lets the box touch them.

Fix on the lid B with two pins for pivots, and fit a little catch made of brass wire. To give extra security, drive ordinary pins, cut off to 5/8 inch, through the sides into fixed B, CC, and DD, and through EE into A. This is an easy enough business if pilot holes are made with a very fine awl or a tiny drill, and a small, light hammer is used. It now remains only to go over the whole box with glass paper or emery cloth, and to glue a diamond of coarse glass paper to one end for striking the matches on.

Note that the lid must not be opened when the box is down, as it would be wrenched off its pivots.

The box illustrated by Fig. 181 was copied from an article of Norwegian manufacture. Its construction is an extremely simple matter, provided that one can get a piece of easily bent wood (birch, for instance), not exceeding 3/16 inch in thickness, for the sides.

[Illustration: FIG. 180.—Showing how to draw an ellipse.]

[Illustration: FIG. 181.—Norwegian workbox.]

The bottom of the box is made of 5/16 or 3/8 inch wood, cut to an oval or elliptical shape. To mark out an ellipse about 8 inches long and 5-1/2 inches wide—this will be a. convenient size—stick two pins into the board 5-1/8 inches apart, pass a loop of thread 14 inches in circumference round these, and run the point of a pencil round the pins in the path which it has to take when confined by the slack of the loop (Fig. 180). Fret-saw along the line.

The wood strip for the side is 4-1/2 inches deep, and 1-1/2 inches longer than the circumference of the bottom. The ends are thinned off somewhat, as shown in Fig. 181, to prevent the lap having a clumsy appearance, and the surface is smoothed all over with sandpaper. Bore a number of small nail holes 3/16 inch from one edge, and then steam the wood over a big saucepan or other suitable vessel until it is quite lissom.

When attaching the side piece to the bottom, begin at the middle, and work first towards what will be the inside end of the lap, and then towards the outside end. Nails are driven in through the holes already drilled. When nailing is finished, clip the top of the overlap with a hand-vice or screw spanner, to prevent the tops of the ends sliding over one another, and bore a line of holes l/4 inch apart, and at the same distance from the outer end. Fine copper wire drawn to and fro through alternate holes from one end of the row to the other and back again, will secure the joint.

The lid overlaps the side 1/4 inch in all directions and has a square notch cut in it at one end to pass under the piece A, and at the other a deeper, circular-ended nick to enable it to pass over the key B when that is turned into the position shown in the illustration. A is cut out of 1/4-inch wood; B, in one piece, out of 1/2-inch. Their length under the heads exceeds the inside depth of the box by the thickness of the lid.

A is affixed rigidly to the side by small screws or wire, while B must be attached in a manner, which will allow the head to rotate. Cut two nicks round the shank, and two horizontal slots at the same height through the end of the box. A couple of brass rings must then be procured of such a size that, when flattened into a somewhat oval shape, they will project beyond the slots sufficiently to allow a piece of wire to pass through them and prevent their being drawn back again.

Quarter-inch wood will do for the lid. A handle is made out of a couple of inches of small cane bent into a semicircle, let through the lid at each end, glued, and cut off flush.

The exterior may be decorated by a design in poker-work, or be stained and varnished. This is left to the maker's discretion.

[Illustration: FIG. 182.—Peg marked for cutting and drilling.]

The expenditure of a halfpenny, and a quarter of an hour's use of a pocket knife, bradawl, and pliers, will produce a toy which is warranted to amuse grown-ups as well as children. Wrestlers made out of clothes pegs may be bought for a copper or two in the street, and are hardly a novelty; yet a few notes on home production will not be a waste of space, as making is cheaper, and much more interesting, than buying.

The clothes pegs used must be of the shape shown in Fig. 182, with a round top. They cost one penny per dozen.

Drill holes through body and legs as indicated in Fig. 182. Cut the legs from the "trunk,'" and whittle them to the shape of Fig. 183. The arms, made out of any thin wood, are 2-1/4 inches long between centres of end holes.

To get the best results the two arms and the four legs should be paired off to exactly the same length.

[Illustration: FIG. 183.—Clothes-peg wrestlers.]

The neatest method of attaching the parts is to use small brass tacks, which must, of course, be of somewhat larger diameter than the holes in the body. Holes in arms and legs are a loose fit, so that the wrestlers may be very loose-jointed, and the tacks must not be driven in far enough to cause any friction.

Instead of tacks one may use wire passed through the parts and secured by a bend or loop at each end. Wire has the disadvantage of entangling the thread which works the figures.

When assembling is finished, bore holes in the centres of the arm pieces, pass a piece of wire through, and twist it into a neat loop at each end. To one loop tie 2 feet of strong thread (carpet thread is best), and to the free end of the thread a large nail or hook. The other loop has 6 feet or so of thread tied to it, to be worked by the hand. If the thread is stained black, it will be practically invisible by artificial light.

The nail or hook is stuck under the edge of the carpet, or into some crack or cranny which affords a good hold, and the wrestlers are worked by motions of the hand. The funniest antics are produced by very slight jerks.

If the arms are set too close together the heads may stick between them, in which case one must either flatten off the sides of the heads or insert fresh arm wires of greater length. If a head persists in jamming against the thread wire or getting under it and staying there, cut 1/2 inch off a pin and stick it into the