Dental review; devoted to the advancement of dentistry. . r theproportion received by the patient. DEMONSTRATION. We have an apparatus familiar to every student of elementaryphysics, only in this case the balls are made of hardened steel. Theyare, in fact, antifriction balls, such as are used in turntables, etc. ORIGINAL COMMUNICA TIONS 323 The same as in bicycles, except these are larger. Steel is usedbecause it combines the highest co-efficient with the least ampli-tude. A scale is added at each end for convenience in measuringthe reaction. For the first experiment we lift one ball to the fu
Dental review; devoted to the advancement of dentistry. . r theproportion received by the patient. DEMONSTRATION. We have an apparatus familiar to every student of elementaryphysics, only in this case the balls are made of hardened steel. Theyare, in fact, antifriction balls, such as are used in turntables, etc. ORIGINAL COMMUNICA TIONS 323 The same as in bicycles, except these are larger. Steel is usedbecause it combines the highest co-efficient with the least ampli-tude. A scale is added at each end for convenience in measuringthe reaction. For the first experiment we lift one ball to the full length of thescale and let it fall. As a result of the impact the opposite ballflies off almost to the full length of the scale, and as it dropsback the operation is repeated again and again, until they graduallycome to rest. But we find only two balls are affected, the two onthe outside, the other six remaining at rest. From this we can make several deductions. The principal oneis. that in using the mallet on a steel plugger the force is transmitted. almost entirely, so that we may consider the blow as delivereddirectly on the filling. Next we see that the penetration of the force of the blowdepends entirely on the weight of the body delivering it. Thus—we raise two balls, letting them fall together, we see the same phe-nomena repeated except that two balls are driven off from the otherend, and they gradually come to rest as before, but always twoballs moving from each end. And the same with three balls. Wethus show that the penetration of the blow depends entirely on theweight of the moving body, and that the tension or intensity ofthe force depends on the velocity. 324 THE DENTAL REVIEW. We now take a lead ball weighing times the steel ones, butwith a very low co-efficient. Letting it fall as before we see that itmoves the further ball less than half the length of the scale, showinga low tension but deep penetration as three balls are moved. Wenow cover the steel ball w
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