Previous arrangements having been made, it will be well, to avoid accidents, for No. 2 to partially inflate the balloon by a fan. Were this precaution not taken, it might happen that flame driven against the tissue-paper might set it on fire. Those who have not tried the experiment little know what power there is in a fan to set up and keep going a current of air. Sometimes people revive a sluggish fire by hanging a sheet of paper in front of it, but a far better application of the paper is to squeeze it into a rough fan and begin fanning. My attention was first called to this fire-fanning process when, travelling in Andalusia, I wanted some chocolate in a hurry, at a lonely wayside posada. A damsel, fan in hand, lighted a bit of charcoal with a paper spill, laid it on the stove grating, put other charcoal round it, the chocolate-pot over all, and began fanning.
You are now ready to learn how much weight your balloon will carry. You will have attached the car, of course. You will have laid your bit of sponge on the tin pan already attached, and you will have remembered to steady the sponge and keep it from falling out by passing a little iron binding wire over the surface of it, and attaching the wire to the tin pan. All this having been done, you are to pour the spirits of wine upon the sponge and set fire to it. Presently the balloon, becoming charged with hot air, will fill out and rise. When risen, be prepared with your money—farthings. Throw in farthing upon farthing until your balloon not only can carry no more, but comes down. Let it come down, and let the spirit flame burn quite out. Any attempt at blowing it out would probably set the balloon in a blaze.
You have gained now the information required; you have learned what weight, when the serious time of letting off arrives, your balloon will carry. Count the farthings and make a memorandum of their weight. There is no particular mystery in the choice of farthings; they are cheap enough, and they are small enough. Sovereigns and half-sovereigns will do quite well, and if you are sufficiently ‘warm’ in pocket-money, you may employ them instead of farthings, over which they present the advantage of recording the actual weight. A sovereign newly minted weighs one hundred and twenty-three grains and a small fraction; a half-sovereign half that weight. Taking one sovereign with another, you may assume one hundred and twenty-three grains to be the weight of each. Here, by the way, I may mention that, having weighed hundreds of sovereigns for the sake of a lazy experiment, I never yet met with two of exactly the same weight.
Fig. 9.—LETTING OFF THE BALLOON.
A fire-balloon is a pretty device of itself, but it becomes much better worth looking at when it is made to take up fireworks, so I will now give some instructions about these fireworks. I cannot recommend you to make the fireworks yourselves, but to buy them ready made and arrange them in suitable devices. You will want a few feet of Bickford’s fuse, and the same of quickmatch. Both may be obtained of Messrs. Brock, of Cheapside and the Crystal Palace.
Fig. 10.—BICKFORD’S FUSE.
Fig. 11.