# Recreations in Mathematics and Natural Philosophy ..

Longman, Hurst, Rees, Orme, and Brown, 1814 - Scientific recreations
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### Popular passages

Page 67 - But since the mean synodic motion of the moon is at the rate of 30" per minute, it follows that the duration of a total solar eclipse can never exceed four minutes.
Page 75 - One place also is higher than another, or out of level with it, when it is farther from the centre of the earth ; and a line equally distant from that centre in all its parts, is called the line of true levei.
Page 399 - The train or match must be of the same composition as that employed for loading ; otherwise the dilatation of the air contained in the hole made by the piercer, would cause the jet to burst. Clayed rockets may be pierced with two holes near the neck, in order to have three jets in the same plane. If a kind of top, pierced with a number of holes, be added to them, they will imitate a bubbling fountain. Jets intended for representing sheets of fire ought not to be choaked.
Page 158 - Thirty days hath September, April, June, and November ; All the rest have thirty-one, Except the second month alone, Which has but twenty-eight, in fine, Till leap year gives it twenty-nine.
Page 402 - Iv is to the Chinese also that we are indebted for this method of representing figures with fire. For this purpose, take sulphur reduced to an impalpable powder, and having formed it into a paste with starch, cover with it the figure you are desirous of representing on fire : it is here to be observed, that the figure must first be coated over with clay, to prevent it from being burnt. When the figure has been covered with this paste, besprinkle it while still moist with pulverised gunpowder; and...
Page 368 - It is evident there must be at least three rods, pierced in proportion to the diminution of the piercer, in order that the powder which is rammed in by means of a mallet, may be uniformly packed throughout the whole length of the rocket. It may be easily perceived, also, that these rods ought to be made of some very hard wood, to resist the strokes of the mallet. In loading rockets it is more convenient not to employ a piercer. When loaded on a nipple, without a piercer, by means of one massy tod,...
Page 396 - ... it ought to be put into a large iron mortar, and to be loaded with a quantity of powder proportioned to the weight of the globe. This small mortar must be of light wood, or of paper pasted together, and rolled up in the form of a cylinder, or truncated cone, the bottom excepted ; which, as already said, must be of wood. The chamber for the powder...
Page 381 - ... wrap up the star in any thing but prepared tow ; because, when made of such paste, it can retain its spherical figure. There will be no need also of piercing a hole in it, to receive the match ; because^ when newly made, and consequently moist, it may be rolltd in pulverised gunpowder, which wijl adhere to it.
Page 375 - ... of the rocket. It must however be observed, that rockets of this kind will not keep longer than a week ; because the moisture contracted by the saltpetre rusts the iron-filings, and destroys the effect they are intended to produce. But the Chinese have long been in possession of a method of rendering...
Page 374 - At the moment when the powder begins to inflame, its expansion produces a torrent of elastic fluid, which acts in every direction ; that is, against the air which opposes its escape from the cartridge, and against the upper part of the rocket ; but the resistance of the air is more considerable than the weight of the rocket, on account of the extreme rapidity with which the elastic fluid issues through the neck of the rocket to throw itself downwards, and therefore the rocket ascends by the excess...