Text-book of medical and pharmaceutical chemistry . irectly in line with the rest. The motion or impulse passesalong the line, but the one at the opposite end is the only oneseen to move. It may be illustrated by placing a ruler on the table, holding it firmly in place,with a marble in contact withone end, and with a hard bodystriking a short quick blow atthe other. The stick, as a whole,does not move, but the jar willbe felt to pass under the hand,and the marble will move fromits place. A frequent class room illustration ofthe transmission of force is that repre-sented in Fig. 10. A number of
Text-book of medical and pharmaceutical chemistry . irectly in line with the rest. The motion or impulse passesalong the line, but the one at the opposite end is the only oneseen to move. It may be illustrated by placing a ruler on the table, holding it firmly in place,with a marble in contact withone end, and with a hard bodystriking a short quick blow atthe other. The stick, as a whole,does not move, but the jar willbe felt to pass under the hand,and the marble will move fromits place. A frequent class room illustration ofthe transmission of force is that repre-sented in Fig. 10. A number of woodor ivory balls are suspended by cordsso that they touch one another whenat rest. On raising A to the positionrepresented in the cut, and allowing itto fall against the ball C, none of the balls are seen to move except B, which iscarried on to the position b. As it returns to strike its neighbor the hall A isthrown off to a less distance than it was at first carried. The other balls remainat rest but transmit the force along the line. Fig. LIGHT. 33 35. Color and Intensity.—It is evident that these oscil-lations may differ in rapidity or in their amplitude ; /. e., compar-ing them to the movements of a pendulum, they may vibraterapidly or slowly, and they may swing a long or short the extent and rapidity of these oscillations depend two im-portant differences in the effects of light on the organs of vision,viz., color and brilliancy ; the brilliancy depending upon the forceof the blows upon the retina, and the color upon the number in agiven time. We have an analogous fact in sound. Here we canmore easily demonstrate the truth of the fact that the intensityof the sound depends upon the amplitude of the vibrations ofthe molecules, while the pitch depends upon the number of wavesor pulsations which reach the ear in a given time. From wellestablished data, we are able to calculate the rapidity of the oscil-lations which produce the different sensations of
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