The writer has clearly shown the interchange of thermic and dynamic energy at the point of junction of the bars of a thermo-electric element of antimony and bismuth, and he has also pointed out that the dynamic nature of electric energy is not less clearly indicated by the long-known fact that an ordinary voltaic current always commences with a rush, as it were, the instant that the circuit is closed. The dynamic cause of this is clearly pointed out by an experiment due to the genius of Prof. Wheatstone. If a tuning-fork, the tail of which is inserted longitudinally into a wooden handle, like a file or chisel, be made to vibrate, and the end of the handle rested obliquely on a table, the resonance of the table will instantly be heard; but on moving the diapason parallel to itself in any election on the table, the resonance ceases, from the perpetual interference of the successive planes of vibration with each other. But now comes the illustration:—On arresting the motion of translation, the resonance immediately recommences, but with a rush or momentary increase of sound: this must unquestionably arise from the resistance offered by the inertia of the molecules of wood to the recommencement of wave-motion; and the parallel phenomenon in electricity may undoubtedly be similarly accounted for. And the reflex momentary current (the terminal extra-current of Faraday), which is well known to take place at the instant of opening the circuit, is equally susceptible of a dynamic interpretation: it is the analogue of the wave reflected from the fixed end of a stretched cord, after having been imparted by the hand to the free end. The hair was taken from a lad aged seven years and a half, a gentleman’s son; he is reported as being “an active, healthy boy, quick and intelligent.” He was delicate up to the age of four, having suffered in quick succession the diseases of childhood, a severe attack of croup, and several attacks of convulsions. The change in the appearance of the hair was first noticed when he was between two and three years old, and increased perceptibly during the last two years. There is no similar alteration of structure of the eyebrows and eyelashes. His complexion is dark, while that of a younger brother is fair; and the latter is free from any alteration of the hair. The dynamic nature of electric energy is clearly indicated by the dynamo-electric machine of Holtz, in which dynamic is directly converted into electric energy,—and by the cognate machines of Wilde, Wheatstone, Siemens, and Ladd, in all of which alike there is an intervening conversion of dynamic into magnetic energy. The enormous amount of current-energy evolved in Mr. Wilde’s machine when the power of a steam-engine is employed to rotate the armatures may be judged of by the fact that a lag piece of platinum wire 0·2 inch in thickness was seen to be disintegrated and partially fused. It is difficult to conceive that in these stances dynamic energy can be converted into magnetic “fluid,” and tat again into thermic energy: the conversion of motion into matter, and the subsequent reconversion of matter into motion, are obviously impossible.
Numerical Evaluation and Experimental Test on a New Giant Magnetostrictive Transducer with Low Heat Loss Design
