Electrical and magnetical experiments.- v. 4. Experiments in pneumatics, hydrology, and pyrotechnics, with an appendix of miscellaneous recreations

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Página 82 - To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. To the end of the twine next the hand is to be tied a silk ribbon, and where the silk and twine join a key may be fastened.
Página 62 - Two small hemispheres of wood are then fixed with cement to the middle of the upper and under sides, centrally opposite, and in each of them a thick strong wire eight or ten inches long, which together make the axis of the wheel. It turns horizontally on a point at the lower end of its axis, which rests on a bit of brass cemented within a glass salt-cellar. The...
Página 100 - PROVIDE a glass cylinder, three feet long, and three inches diameter ; near the bottom of it fix a brass plate, and have another brass plate, so contrived that you may let it down the cylinder, and bring it as near the first plate as you desire. Let this cylinder be exhausted and insulated, and when the upper part is electrified, the electric...
Página 85 - ... fo near, and called aloud to all the company to retire, as he did himfelf about two feet. THINKING himfelf now fecure enough, and not being incommoded by any body very near him, he took notice of what...
Página 238 - ... he thinks proper, then to close the box, and, if he please, to wrap it up in paper, seal it, and give it to you. Then placing the board with the pyramid upon it, you immediately tell him the order in which the tablets are placed, by reading the words to which the needles on the circles point. INTERESTING EXPERIMENTS WITH THE AIR PUMP.
Página 56 - ... can touch the face of the king without danger, which he pretends is a test of his loyalty. The Cup of Tantalus. You place a cup of any sort of metal on a stool of baked wood or a cake of wax. Fill it to the brim with any liquor; let it communicate with the branch by a small chain; and when it is moderately electrified, desire a person to taste the liquor, without touching the cup with his hands, and he will instantly receive a shock on his lips. The motion of the wheel being stopped, you taste...
Página 59 - ... wheel, it will attract the nearest thimble, and so put the wheel in motion ; that thimble, in passing by, receives a spark, and thereby being electrified is repelled, and so driven forwards ; while a second, being attracted, approaches the wire, receives a spark, and is driven after the first, and so on till the wheel has gone once round, when the thimbles before electrified approaching the wire, instead of being attracted as they were at first, are repelled, and the motion presently ceases....
Página 63 - ... inches distance, with a thimble on the top of each. On the edge of the wheel is a small leaden bullet, communicating by a wire with the gilding of the upper surface of the wheel ; and about six inches from it is another bullet, communicating in like manner with the under surface. When the wheel is to be charged by the upper surface, a communication must be made from the under surface to the table.
Página 55 - ... together, by which the picture will appear of a piece, as at first, only part is behind the glass, and part before. Hold the picture horizontally by the top, and place a little moveable gilt crown on the king's head.
Página 109 - ... an hour . If after this, it be drawn through the hand either way, the light will be uncommonly intenfe, and, without the leaft interruption, from one hand to the other, even to its whole length. After this operation, which difcharges it in a great meafure, it will ftill flafh at intervals, though it be held only at one extremity, and quite ftill ; but if it be -grafped by the other hand at the fame time, in a different place, ftrong...

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