Dynamometers

Abstract

THE late Mr. Jervis-Smith, a vicar at Taunton until in 1886—he took charge of the Millard engineering laboratory at Oxford, was a very modest and ingenious enthusiast in the experimental study of natural science. He was particularly absorbed in the study of methods of measuring mechanical power. A dynamometer measures the product of force into velocity. The chemical balance illustrates the great accuracy with which we can measure force and there is also great accuracy possible in measuring speed, but the measurement of their product with accuracy is a very different thing. To measure the electrical power given out by or given to a machine is very easy; however large or small the power may be, our measurements may be made accurate to the fourth or even to the fifth,significant figure. It is only in very exceptional cases that the measurement of mechanical power is correct to two significant figures. Dynamometers. By Rev. F. J. Jervis-Smith. Edited and Amplified by Prof. C. V. Boys. Pp. xvi + 267.(London: Constable and Co., Ltd., 1915). Price 14s. net.