The Relation of Science and Religion.pdf - Online Christian Library

96 SCIENCE AND RELIGION.here has been described as the difference between energy of position and energy of motion."Both of these must be taken into account inorder to have a full view of the facts. ENER-GY OF POSITION, is illustrated by a water-head,or reservoir, where an accumulation of wateris laid up in store, ready to be drawn upon formotive power when machinery set up in a positionsomewhat lower is to be brought into actionand made to do the work for which it hasbeen constructed. ENERGY OF MOTION is seenwhen the storehouse of water is opened andthe rush of the current sweeps along the preparedchannel descending upon the greatwheel, which sets in motion the whole machinery.In such a case as this, the amountof work done by the revolutions of the greatwheel is an exact measure of the amountof water which has passed to a lower level.Or let us suppose there is only a limited supplyin the water-head, and that there are nofeeders, but that the streamlets and springsfrom which it is supplied, have ceased to flow,and let us suppose that the mill comes to astand because of failure of motive power, theamount of work done up to that moment isthe measure of the energy stored in the water-* See Appendix III.