. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. OJECTING. being equal to the sum of the two amplitudes. If theirphases are opposite, so that one reaches its upper limitat the same instant that the other reaches its lowerlimit, then the spot of light will not be drawn out into aline at all, but will remain quiescent. These variousrelative vibrations can only be obtained by trial, butusually in four or five strokes one will develop such aphase as he requires. IV. Resultants, Keeping the two forks in unison
. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. OJECTING. being equal to the sum of the two amplitudes. If theirphases are opposite, so that one reaches its upper limitat the same instant that the other reaches its lowerlimit, then the spot of light will not be drawn out into aline at all, but will remain quiescent. These variousrelative vibrations can only be obtained by trial, butusually in four or five strokes one will develop such aphase as he requires. IV. Resultants, Keeping the two forks in unison,turn the second fork so that it vibrates the light so that it falls upon the second mirroras before, and thence to the middle of the , if both forks be struck, the resulting figure maybe a straight line, an ellipse, or a circle depending Fig. 50. upon the phase of the first fork when the second onebegins to vibrate. Fig. 50 represents these unisonforms. By moving one of the slides so that the fork isnot quite in tune with the other, the figure will movethrough each of these phases alternately. When the. Fig. 51. circle is obtained upon the screen, swing the secondfork through a small arc, and the circle will be drawnout into a luminous scroll, (Fig. 51). If the forks are ACOUSTICS, 73 not quite in unison, the same experiment will give thescroll of irregular amplitude, (Fig. 52).
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherbosto, bookyear1877
