The London, Edinburgh and Dublin Philosophical Magazine and Journal of Science

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Taylor & Francis, 1878

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Side 306 - CLIFFORD — THE ELEMENTS OF DYNAMIC. An Introduction to the Study of Motion and Rest in Solid and Fluid Bodies.
Side 49 - ... in motion ; and the instrument on the board, reacting through the microphone, causes a continuous sound to be produced, which is permanent so long as the independent current of electricity is maintained through the microphone. It follows that the question of providing a relay for the human voice in telephony is thus solved.
Side 45 - The problem which the microphone solves is this — to introduce into an electrical circuit an electrical resistance, which resistance shall vary in exact accord with sonorous vibrations, so as to produce an undulatory current of electricity from a constant source, whose wave-length, height, and form shall be an exact representation of the sonorous waves.
Side 50 - It is easy to speculate on the causes of such behavior, and it may be suggested that the reason of the non-appearance of a dark line may be that the intensity of the light from a great thickness of ignited oxygen overpowers the effect of the photosphere...
Side 61 - Borealis. In other cases, again, it is possible that the composition of a star's atmosphere may be of such a nature as to lead to a state of periodically unstable chemical equilibrium ; that is to say, during a certain period combination may be going on with the accompanying evolution of heat, till at length dissociation again begins to take place. In this manner the phenomena of many variable stars may perhaps be accounted for.
Side 144 - ... and to Sir W. Thomson belongs the credit of having established the fact by experiment, irrespective of his theoretical deductions from the facts of thermo-electricity. He thus describes his decisive experiment : — " A metal bar insulated so as to be movable about an axis perpendicular to the plane of a metal ring made up half of copper and half of zinc, the two halves being soldered together, turns from the zinc towards the copper when positively electrified, and from the copper towards the...
Side 48 - I am inclined to believe, from numerous experiments, that the whole block increases and diminishes in size at all points, in the centre as well as the surface, exactly in accordance with the form of the sonorous wave. Confining our attention, however, to points on A and B, how can this increased molecular size or form produce a change in the electrical waves ? This may happen in two ways : first, by increased pressure on the upper surface, due to its enlargement ; or, second, the molecules themselves,...
Side 132 - J- increased regularly, without discontinuity, in passing from several degrees below the freezing point to several degrees above it. We drew attention to the fact that, in consequence of the absorbed charge in water being immeasurably greater than the surface-charge, we could not hope, by any method of experimenting, to properly compare- the true specific inductive capacity with the index of refraction for light of infinitely long waves ; so that, in fact, the only support that Prof. C.
Side 456 - ... when unpolarized light falls on its surface and it is seen through a Nicol whose principal section is vertical, and when the incident light is polarized perpendicularly to the plane of incidence and it is seen directly. These experiments show that when light falls upon the surface of a film of iodine at an angle of about...
Side 49 - ... sound to be produced, which is permanent so long as the independent current of electricity is maintained through the microphone. It follows that the question of providing a relay for the human voice in telephony is thus solved. " The transmission of sound through the microphone is perfectly duplex ; for if two correspondents use microphones as transmitters, and telephones as receivers, each can hear the other, but his own speech is inaudible ; and if each sing a different note, no chord is heard....

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