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The Great Events by Famous Historians [Volumes 1-14]
- Автор: Gutenberg
- Год: 1905
- Язык: английский
- Жанр: История
Электронная книга - «The Great Events by Famous Historians [Volumes 1-14]». Краткое содержание книги:
The Great Events by Famous Historians, Volume 01
The Great Events by Famous Historians, Volume 02 / (From the Rise of Greece to the Christian Era)
The Great Events by Famous Historians, Volume 03
The Great Events by Famous Historians, Volume 04
The Great Events by Famous Historians, Volume 05 / (From Charlemagne to Frederick Barbarossa)
The Great Events by Famous Historians, Volume 06 / (From Barbarossa to Dante)
The Great Events by Famous Historians, Volume 07
The Great Events by Famous Historians, Volume 08 / The Later Renaissance: from Gutenberg to the Reformation
The Great Events by Famous Historians, Volume 09
The Great Events by Famous Historians, Volume 10
The Great Events by Famous Historians, Volume 11
The Great Events by Famous Historians, Volume 12
The Great Events by Famous Historians, Volume 13
The Great Events by Famous Historians, Volume 14
The Great Events by Famous Historians, Volume 17
The Great Events by Famous Historians, Volume 21 / The Recent Days (1910-1914)
"The first thing is the wonderful effect of pointed bodies, both in drawing off and throwing off the electrical fire. For example:
"Place an iron shot of three or four inches diameter on the mouth of a clean, dry glass bottle. By a fine silken thread from the ceiling, right over the mouth of the bottle, suspend a small cork ball about the bigness of a marble, the thread of such a length as that the cork ball may rest against the side of the shot. Electrify the shot, and the ball will be repelled to the distance of four or five inches, more or less, according to the quantity of electricity. When in this state, if you present to the shot the point of a long, slender, sharp bodkin, at six or eight inches distance, the repellency is instantly destroyed, and the cork flies to the shot. A blunt body must be brought within an inch and draw a spark to produce the same effect. To prove that the electrical fire is drawn off by the point, if you take the blade of the bodkin out of the wooden handle and fix it in a stick of sealing-wax, and then present it at the distance aforesaid, or if you bring it very near, no such effect follows; but sliding one finger along the wax till you touch the blade, the ball flies to the shot immediately. If you present the point in the dark you will see, sometimes at a foot distance and more, a light gather upon it, like that of a firefly or glow-worm; the less sharp the point, the nearer you must bring it to observe the light; and at whatever distance you see the light you may draw off the electrical fire and destroy the repellency. If a cork ball so suspended be repelled by the tube, and a point be presented quick to it, though at a considerable distance, it is surprising to see how suddenly it flies back to the tube. Points of wood will do near as well as those of iron, provided the wood is not dry, for perfectly dry wood will no more conduct electricity than sealing-wax.
"To show that points will throw off as well as draw off the electrical fire, lay a long sharp needle upon the shot, and you cannot electrize the shot so as to make it repel the cork ball. Or fix a needle to the end of a suspended gun-barrel or iron rod so as to point beyond it like a little bayonet, and while it remains there the gun-barrel or rod cannot, by applying the tube to the other end, be electrized so as to give a spark, the fire continually running out silently at the point. In the dark you may see it make the same appearance as it does in the case before mentioned.
"The repellency between the cork ball and the shot is likewise destroyed, 1st, by sifting fine sand on it—this does it gradually; 2dly, by breathing on it; 3dly, by making a smoke about it from burning wood; 4thly, by candle-light, even though the candle is at a foot distance—these do it suddenly. The light of a bright coal from a wood fire, and the light of a red-hot iron, do it likewise, but not at so great a distance. Smoke from dry rosin dropped on hot iron does not destroy the repellency, but is attracted by both shot and cork ball, forming proportionable atmospheres round them, making them look beautifully, somewhat like some of the figures in Burnet's or Whiston's Theory of the Earth.
"N.B.—This experiment should be made in a closet where the air is very still, or it will be apt to fail.
"The light of the sun thrown strongly upon both cork and shot by a looking-glass, for a long time together, does not impair the repellency in the least. This difference between firelight and sunlight is another thing that seems new and extraordinary to us.
"We had for some time been of opinion that the electrical fire was not created by friction, but collected, being really an element diffused among and attracted by other matter, particularly by water and metals. We had even discovered and demonstrated its afflux to the electrical sphere, as well as its efflux, by means of little, light windmill wheels made of stiff paper vanes fixed obliquely, and turning freely on fine wire axes; also by little wheels of the same matter, but formed like water-wheels. Of the disposition and application of which wheels, and the various phenomena resulting, I could, if I had time, fill you a sheet. The impossibility of electrizing one's self, though standing on wax, by rubbing the tube, and drawing the fire from it; and the manner of doing it by passing it near a person or thing standing on the floor, etc., had also occurred to us some months before. Mr. Watson's ingenious Sequel came to hand; and these were some of the new things I intended to have communicated to you. But now I need only mention some particulars not hinted in that piece, with our reasonings thereupon; though perhaps the latter might well enough be spared.
"1. A person standing on wax and rubbing the tube, and another person on wax drawing the fire, they will both of them (provided they do not stand so as to touch one another) appear to be electrized to a person standing on the floor; that is, he will perceive a spark on approaching each of them with his knuckle.
"2. But if the persons on wax touch one another during the exciting of the tube, neither of them will appear to be electrized.
"3. If they touch one another after exciting the tube, and drawing the fire as aforesaid, there will be a stronger spark between them than was between either of them and the person on the floor.
"4. After such strong spark neither of them discover any electricity.
"These appearances we attempt to account for thus: We suppose, as aforesaid, that electrical fire is a common element, of which every one of the three persons above mentioned has his equal share, before any operation is begun with the tube. A, who stands on wax and rubs the tube, collects the electrical fire from himself into the glass; and, his communication with the common stock being cut off by the wax, his body is not again immediately supplied. B (who stands on wax likewise), passing his knuckle along near the tube, receives the fire which was collected by the glass from A; and his communication with the common stock being likewise cut off, he retains the additional quantity received. To C, standing on the floor, both appear to be electrized; for he, having only the middle quantity of electrical fire, receives a spark upon approaching B, who has an over quantity; but gives one to A, who has an under quantity. If A and B approach to touch each other, the spark is stronger, because the difference between them is greater. After such touch there is no spark between either of them and C, because the electrical fire in all is reduced to the original equality. If they touch while electrizing, the equality is never destroyed, the fire only circulating. Hence have arisen some new terms among us. We say B (and bodies like circumstanced) is electrized positively; A, negatively. Or rather, B is electrized plus; A, minus. And we daily in our experiments electrize bodies plus or minus, as we think proper. To electrize plus or minus no more needs to be known than this: that the parts of the tube or sphere that are rubbed do, in the instant of the friction, attract the electrical fire, and therefore take it from the thing rubbing; the same parts immediately, as the friction upon them ceases, are disposed to give the fire they have received to any body that has less. Thus you may circulate it as Mr. Watson has shown; you may also accumulate it or subtract it, upon or from any body, as you connect that body with the rubber or with the receiver, the communication with the common stock being cut off. We think that ingenious gentleman was deceived when he imagined (in his Sequel) that the electrical fire came down the wire from the ceiling to the gun-barrel, thence to the sphere, and so electrized the machine and the man turning the wheel, etc. We suppose it was driven off, and not brought on through that wire; and that the machine and man, etc., were electrized minus—that is, had less electrical fire in them than things in common.