Proceedings of the American Academy of Arts and Sciences, Volumen26Metcalf and Company, 1891 Vol. 12 (from May 1876 to May 1877) includes: Researches in telephony / by A. Graham Bell. |
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Página 362 - A Plea for the Constitution of the United States of America, wounded in the House of its Guardians.
Página 116 - ... f Turning now to the observations of Hertz, we find it stated that the material, the resistance, and the diameter of the wire of the micrometer circuit employed by him, have very little influence on the result The rate of propagation of an electrical disturbance along a conductor depends mainly on its capacity and coefficient of self-induction, and only to a small extent on its resistance. Hertz concludes that, owing to the great rapidity of the alternations, the magnetism of the iron is unable...
Página 117 - ... their position unchanged. It follows from this that the velocity of propagation in a wire has a definite value independent of its dimensions and material. Even iron wires offer no exception to this, showing that the magnetic susceptibility of iron does not play any part in the case of such rapid motions. It would be interesting to investigate the behaviour of electrolytes in this respect.
Página 351 - He inherited a distinguished name, and his labors have rendered it memorable and illustrious, — one of the brightest in the annals of American surgery, — not to claim for it a still higher place in the history of the healing art.
Página 158 - Roezl, the well known German collector, made to him in 1869 to this effect: that "he found in the State of Guerero a Zea which he thinks specifically distinct, and he thinks undescribed ; the ears very small, ia two rows truly distichous ; the ear (but not each grain separately) covered with a husk, the grain precisely like some varieties of maize, only smaller and harder.
Página 116 - No. 108, 1859, p. 499. there is but little of the mass of the iron magnetized. Even if these instantaneous discharges are capable of magnetizing iron, . . . the electromotive impulses or sudden rushes of electricity do not magnetize the iron, and hence do not find in it any greater self-inductive opposition than they would find in a non-magnetic but otherwise similar conductor.
Página 367 - BANCROFT. and multitude of the papers which have been used, and which could not be intelligently cited, without burdening the pages with a disproportionate commentary." It was apparently Bancroft's intention at that time to cull out for publication such letters as would confirm his narrative, "and possess an intrinsic and general interest by illustrating the character and sentiments of the people during the ten or twelve years preceding the 4th of July. 1776." This purpose he did not carry out. The...
Página 115 - But in the case of a discharge of a leyden-jar iron is of no advantage. The current oscillates so quickly that any iron introduced into the circuit, however subdivided into thin wires it may be, is protected from magnetism by inverse currents induced in its outer skin, and accordingly does not get magnetized, and, so far from increasing the inductance of the discharge circuit, it positively diminishes it by the reaction effect of these induced currents; it acts, in fact, much as a mass of copper...
Página 116 - In the experiments on alternative path," as described by Dr. Lodge, " the main result is very briefly summed up by saying that, where a sudden discharge had to pass through a conductor, it was found that iron and copper acted about equally well, and indeed iron sometimes exhibited a little superiority, and that the thickness of the conductor and its ordinary conductivity mattered very little indeed. In the case of enormously...
Página 115 - ... current some 5000 times by the use of iron. But in the case of the discharge of a Leyden jar, iron is of no advantage. The current oscillates so quickly that any iron introduced into its circuit, however subdivided into thin wires it may be, is protected from magnetism by inverse currents induced in its outer skin...