Electricity in the service of man: a popular and practical treatise on the applications of electricity in modern life (Google eBook)

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Cassell & Company, limited, 1886 - Science - 859 pages
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Page 843 - ... of business; it has enabled man to descend to the depths of the sea, to soar into the air, to penetrate securely into the noxious recesses of the earth, to traverse the land in cars which whirl along without horses, and the ocean in ships which run ten knots an hour against the wind.
Page 215 - The extraordinary noise caused by the horses' hoofs makes the fish issue from the mud, and excites them to combat. These yellowish and livid eels, resembling large aquatic serpents, swim on the surface of the water, and crowd under the bellies of the horses and mules. A contest between animals of so different an organization furnishes a very striking spectacle.
Page 843 - It has lengthened life; it has mitigated pain; it has extinguished diseases; it has increased the fertility of the soil; it has given new securities to the mariner; it has furnished new arms to the warrior; it has spanned great rivers and estuaries with bridges of form unknown to our fathers; it has guided the thunderbolt innocuously from heaven to earth; it has lighted up the night with the splendor of the day; it has extended the range of the human vision; it has multiplied the power of the human...
Page 689 - I am inclined to view with more favour the idea that an infinite variety of fresh contacts brought into play by •the molecular pressure affords the true explanation. It has the advantage of being supported by the numerous forms of microphone I have constructed, in all of which I can fully trace the effect. I have been very much struck by the great mechanical force exerted by this uprising of the molecules under sonorous vibrations. With vibrations from a musical box 2 feet in length, I found that...
Page 261 - ... which clamps a stout wire rising from the base of the machine. The currents are conveyed from the brushes...
Page 689 - I have never been able to measure it with the simple appliances at my disposal. I have examined every portion of my room — wood, stone, metal, in fact all parts — and even a piece of india-rubber : all were in molecular movement whenever I spoke. As yet I have found no such insulator for sound as gutta-percha is for electricity. Caoutchouc seems to be the best ; but I have never been able by the use of any amount at my disposal to prevent the microphone reporting all it heard. The question of...
Page 207 - In the middle is a cross (b) cut out of sheet aluminium, so that the rays from the negative pole projected along the tube will be partly intercepted by the aluminium cross, and will project an image of it on the hemispherical end of the tube which is phosphorescent...
Page 689 - I found that one ounce of lead was not sufficient on a surface of contact 1 centim. square to maintain constant contact ; and it was only by removing the musical box to a distance of several feet that I was enabled to preserve continuity of current with a moderate pressure. I have spoken to forty microphones at once ; and they all seemed to respond with equal force. Of course there must be a loss of energy in the conversion of molecular vibrations into electrical waves ; but it is so small that I...
Page 689 - ... the blocks A and B ; nor would the upper surface be thrown up if the pressure be removed, as sand is on a vibrating glass. The throwing up of this upper piece B when pressure is removed proves that a blow, pressure, or upheaval of the lower portion takes place — that this takes place there cannot be any doubt, as the surface, considered alone (having no depth), could not bodily quit its mass. In fact, there must have been a movement to a certain depth ; and I am inclined to believe, from numerous...
Page 688 - B should so vary the conductivity or electrical resistance as to throw it into waves in the exact form of the sonorous vibrations ? It cannot be because it throws up the upper portion, making an intermittent current, because the upper portion is fastened to the lower, and the galvanometer does not indicate any interruption of current whatever. It cannot be because the molecules arrange themselves in stratified lines, becoming more or less conductive, as then surfaces would not be required...

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