To Wire the Balloon.
Select a coil of iron wire, a little thicker than a pin; and remove the elasticity, as recommended with coloured gerbes. Before applying it to the balloon, practise the method of making a joining, as shown by fig. 145, simply bringing the ends together, crossing them about an inch from the extremity, and winding them tight round each other. Now lay the balloon, as in fig. 146, with a book, or a flat weight, upon it, to keep it down: curve the wire to the shape of the bottom of the balloon, and lay it about half an inch from the edge. Notch the paper, at the joinings of the gores; paste, and fold back. When perfectly dry, not before, turn the balloon over: cut the wire 2 inches longer than to meet; bend the ends together, and make the joining; paste, and bend over, the remaining half; and shape the wire to a circle. A star, of double-crown, may be pasted on the top, and a thread passed through it, to hold it by. To effect this, open the balloon, pass a book up it, spread the top flat on the book, and paste on it a star, or a circular piece of paper, the size of a penny. If a hole gets torn in it, it can be repaired in the same way.
Take two straight pieces of wire, a little longer than the diameter of the mouth of the balloon; pass them, half way, through a piece of sponge, at right angles to each other; fasten these wires across the mouth; saturate the sponge with wood naphtha, or methylated spirit, taking especial care that not a drop falls on the balloon; get someone to set fire to some pieces of paper on the ground; hold the balloon at a good height above the flame, to prevent the spirit, in the sponge, from catching. Three persons ought to assist in the start: one to manage the burning paper; two to hold the balloon steady, and to keep the mouth open, for the hot air to inflate it. As soon as the balloon gets expanded, set fire to the spirit; and directly it begins to pull against the hand, which it will do, let it go. A balloon of this size will require an ounce of spirit, and as much sponge as will absorb it. See fig. 167.
To project a gore for 24 sheets of tissue paper, let the radius be 71⁄2 inches; for 48 sheets, 10 inches. The shape of the balloon, when expanded, will be the same as fig. 139, rotating on the axis b o. If the pattern gore be projected from fig. 147, the balloon will be pear-shaped, and may be filled with gas, like those started from the Crystal Palace. The paper, 16-lb. double-crown, must have a coat of boiled linseed oil. The bottom should be open, and fitted with a cylindrical neck, about an inch diameter, and 3 inches long, made of writing paper of three thicknesses. Fig. 168 shows the magnesium light attached.
A flat weight may be constructed by making a thin deal box, the size and shape of a lucifer-match box; fill it with melted lead; nail a lid on it, and cover it with pasted paper. The same will serve for a paper-weight.
A spindle, on which to fire wheels, is shown at fig. 148; it is furnished with a fly-nut, which can be taken off, and put on, without trouble. As there is considerable difficulty in obtaining an article of this kind, its place may be supplied by a carriage-bolt, of which hundreds, if necessary, may be procured at the ironmonger's, of lengths varying from 1 inch to 12, or more. One of 6 inches will be suitable for most purposes. As the nut is small, and would be difficult to find, if dropped on the ground, on a dark night, proceed as follows. Turn a piece of beech, about 11⁄2 inch square, and 21⁄2 inches long, into a cylinder, with hemispherical ends, and a hole through it, like a popgun. Cut it, while yet in the lathe, or saw it across into two pieces, one an inch long, the other, an inch and a half. In the flat end of the inch length, mortise a hole, and sink the nut in it; take a circular piece of wood, with a hole bored in the middle, and screw it flat on, over the nut. Fig. 150, a, shows the turned piece; b, the circular piece, screwed on, to keep the nut from falling out. This serves the purpose of the fly-nut of fig. 148. The carriage-bolt is shown, first at fig. 149; then at fig. 150, with the nut screwed on. Take a piece of deal, fig. 155, about 11⁄2 inch square, and 20 inches long: make a hole through at a, and drive the carriage-bolt from behind; the shoulder, being square, will hold firm; in front, at c, slip on the above turned piece of wood, an inch and a half long: the piece, with the nut embedded in it, is, of course, put on at the end, b. The hole through this inch piece should be 1⁄8 of an inch, or more, larger in diameter than the female (or counter) screw of the nut, in order that it may slip on and off with ease. At the top fix a strong wire, d, and file the end round and smooth: at s and x, in the side, fix two screw-eyes, or staples, to receive rocket sticks. At m and n bore two holes, through which it can be screwed to a post. The screw-eye at s ought to be about level with the top of the post. If there is too great a space between w and z, pieces of a roman candle case may be slipped on; but a popgun, sawed into short lengths, is better. Several should be kept in readiness, of different lengths, to suit the naves of different wheels. A piece of iron rod, about half an inch long, and to fit the hole, ought to be driven up furilonas, &c., to rest on the top of d, fig. 155; and the wire should be a little longer than the hole, that the piece may play clear of the upright, the top of which should be hemispherical, as drawn. Fig. 151 is a screw-ring; 152, a screw-eye: 153, a screw-hook; 154, a cup-hook. If a little bit, s, of 152 be sawed, or filed out, it makes a stronger cup-hook than the brass, for match-weights.
[WINGED ROCKETS.]
An 8⁄8 rocket is the smallest size worth making: it is, also, sufficiently large; and, as it requires a machine to fire it from, it is best to keep to one size. The head, fig. 156, may be the same as the external diameter of the case, or it may be slightly enlarged: to receive a parachute, it may be 12, or even 16 inches high; and the top may be closed with a lid, fig. 163, formed of a case choked tight; or by simply stopping it with a piece of turned wood, or with a thin bung, pushed in, as a cork into a bottle. A bung may be readily sawed thin with a fine-toothed saw; if required to be made smaller in diameter, it must be cut round sidewise, not longitudinally. If the head is to receive stars, it must not be above 8 inches high. To construct the wings, take a thin piece of deal, or tin, and cut out a right-angled triangle, fig. 157. Make a b = 71⁄2 inches, b c = 11⁄2 inch. Take a piece of imperial brown paper, 8 inches long, 4 broad, and fold it down the middle lengthwise, so as to become 8 by 2. Lay the sloping edge, a c, of fig. 157 along the folded edge of the paper, a c, fig. 158, and mark round it, with a pencil. About 3⁄8 of an inch distant, draw the line d e parallel to a b. Cut through with the scissors, and the paper will be of the shape of fig. 158. Bend the shaded parts flat, to form a flap, or kind of hinge. Paste the surface of the two triangles, and press them together to form a double thickness. If this does not make the wing stiff enough, insert, between them, a triangular piece of cardboard, to make it of three folds, like a shirt-collar. Take a piece of sheet tin, or a piece of cardboard, fig. 161. Let m n be 7 inches; and m p such that it shall exactly wind round the rocket. Divide it into 3 equal parts, by the parallel lines r and s, and at each end cut out little pieces, as shown at a a, &c. Now, if this be wound round the rocket, marks can be made through the slits a a, with a blacklead pencil, or with a stencil-brush, dipped into blacklead powder, such as used for polishing grates. These marks will indicate the places for the wings. Paste or glue them on, and secure the joinings with another slip of paper pasted over them, as shown by the dotted lines, beside the wings, fig. 156. The wings will branch out at angles of 120° divergence from each other, like the lines a a, b b, c c, fig. 162. The rocket is thus winged; and, so far, complete.