An Introduction to Natural Philosophy: Illustrated with Copper Plates, Volume 2

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J. Johnson, 1790

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Page 354 - ... in which there was a shed convenient for his purpose. But dreading the ridicule which too commonly attends unsuccessful attempts in science, he communicated his intended experiment to nobody but his son, who assisted him in raising the kite.
Page 285 - ... let this mixture be rammed into a crucible of about an inch and a half in depth, till it be almoft full ; and let it be placed in...
Page 353 - The Doctor, having published his method of verifying his hypothesis concerning the sameness of electricity with the matter of lightning, was waiting for the erection of a spire in Philadelphia to carry his views into execution, not imagining that a pointed rod of a moderate height could answer the purpose, when it occurred to him that by means of a common kite he could have better access to the regions of thunder than by any spire whatever.
Page 344 - Hj fastened to the tube by means of a cork; the upper extremity of the wire projects about a quarter of an inch above the tube, and screws into the brass cap...
Page 249 - Ceruse), is made by rolling leaden plates spirally up, so as to leave the space of about an inch between each coil, and placing them vertically in earthen pots, at the bottom of which is some good vinegar. The pots are...
Page 260 - ... into cold water. This is called tempering. The hardnefs produced is greater in proportion as the fteel is hotter and the water colder. Hence arifes the...
Page 260 - The charcoal dull may be made of bones, horns, leather, and hairs of animals, or -of any of thefe ingredients after they are burned in a clofe veflel till they are black : thefe being pulverized, and mixed with wood-aihes, muft be well mixed together.
Page 258 - Charcoal, or coke with lighted brufliwood, is firft thrown in : and when the infide of the furnace has acquired a ftrong ignition, the ore is thrown in by fmall quantities at a time, with more of the fuel ; and commonly a portion of lime-ftone is thrown alfo, as a flux.
Page 277 - If half a pound of this be dried before a fire, and afterwards suffered to cool for about an hour, and it be then loosely mixed or kneaded with two ounces of linseed oil ; the whole, in something more than half an hour, becomes gradually hot, and at length bursts into flame.
Page 361 - ... branches over a large tract of country, the lightning is seen to dart from one part of it to another, and often to illuminate its whole mass. When the cloud has acquired a sufficient extent, the lightning strikes between the cloud and the earth, in two opposite places; the path of the lightning lying through the whole body of the cloud and its branches. The longer this lightning continues, the...

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