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alternating current ampere apparatus arc lamp armature arranged atoms attracted automatic bell brush cable called carbon cause cell centimetre chapter chemical circuit coil of wire conductor connecting wires copper corpuscles current passing direction disc distant dynamo earth effect electric current electric pressure electric waves electrical discharge electrified electro-magnet electrode electrolytic energy ether ether waves experiment filament furnace galvanometer glass glow lamp heat hydrogen induction coil instrument insulated iron leading-in leading-out lever light Lord Armstrong machine magnetic field means measure merely messages metal miles Morse Morse code motor moving necessary needle operator ordinary overhead wire oxygen piece placed plate platinum pole produced rail rate of flow receiver require resistance revolving ring round signals simple spark station stationary subscriber switch telegraph telephone temperature tion transmitter tube unit vibrations volts wireless telegraphy words X-rays zinc
Page 284 - Volt, and was defined as the pressure necessary to send a current of one ampere through a resistance of one ohm.
Page 241 - The thing is practicable in this way : " We know that sounds are made by vibrations, and are adapted to the ear by the same vibrations which are reproduced by the intervening medium. But the intensity of the vibrations diminishes very rapidly with the distance : so that it is, even with the aid of speaking-tubes and trumpets, impossible to exceed somewhat narrow limits.
Page 242 - Suppose that a man speaks near a movable disk, sufficiently flexible to lose none of the vibrations of the voice; that this disk alternately makes and breaks the connection with a battery; you may have at a distance another disk which will simultaneously execute the same vibrations.
Page 339 - ... the centimetre as the unit of length, the gramme as the unit of mass, and the second as the unit of time.
Page 323 - ... engaged in writing. But this was not all: Newton saw in the cosmic circulation and the mutual convertibility of rare and dense forms of matter a universal law, and rising to a still bolder conception, which completes his Hypothesis of the Universe, adds : " Perhaps the whole frame of nature may be nothing but various contextures of some certain etherial spirits or vapours, condensed, as it were, by precipitation, much after the same manner that vapours are condensed into water, or exhalations...
Page 242 - ... from a battery. You may have at a distance another disc, which will simultaneously execute the same vibrations. ... It is certain that in a more or less distant future speech will be transmitted by electricity. I have made some experiments in this direction. They are delicate, and demand time and patience ; but the approximations obtained promise a favorable result.
Page 322 - THE now well-known kinetic theory of gases is a step so important, in the way of explaining seemingly static properties of matter by motion, that it is scarcely possible to help anticipating, in idea, the arrival at a complete theory of matter, in which all its properties will be seen to be merely attributes of motion.
Page 287 - A power of one watt is produced by a current of one ampere at a pressure of one volt.
Page 305 - ... north pole of one magnet will attract the south pole of another, and the south pole of one will attract the north of another ; but the north...