An Essay on Electricity: Explaining the Theory and Practice of that Useful Science; and the Mode of Applying it to Medical Purposes. With an Essay on Magnetism

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R. Hindmarsh, 1787 - Electric power - 473 pages
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Page 41 - ... 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 electrising, the equality is never destroy'd, the fire only circulating.
Page 41 - 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.
Page 259 - ELECTROMETERS. wire projects about a quarter < of an inch above the tube, and fcrews into the brafs cap EF, which cap is open at the bottom, and ferves to defend the waxed part of the inftrument from the rain, &c.
Page 307 - These balls will, every time they are heated, give the electrical fluid to, or take it from, other bodies, according to the plus or minus state of it within them. Heating them frequently, I find, will sensibly diminish their power ; but keeping one of them under water a week did not appear in the least degree to impair it.
Page 397 - K. put them into a large tub that was more than one-third filled with clean water ; he then, with great labour, worked the tub to and fro for many hours together, that the friction between the grains of iron by this treatment might break off...
Page 419 - Hauing made many and diuers compasses, and using alwaiea to finish and end them before I touched the needle, I found continually, that after I had touched the yrons with...
Page 261 - VII. When the weather is damp, and the Electricity is pretty ftrong, the index of the electrometer, after taking a fpark from the...
Page 377 - ... concentrated. One of the poles points north, and the other south. The magnetic meridian is a vertical circle in the heavens, which intersects the horizon at the points to which the magnetic needle, when at rest, directs itself.
Page 43 - Electric substances are impervious to the two electricities. 7. Either power, when applied to an unelectrified body, repels the power of the same sort, and attracts the contrary.
Page lxviii - ... •'If the mercury in the gage be imperfectly boiled, the experiment will not succeed ; but the colour of the electric light, which in air rarefied by an exhauster is always violet or purple, appears in this case of a beautiful green, and, what is very curious, the degree of the air's rarefaction may be nearly determined by this means ; for I have known instances, during the course of these experiments where...

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