ment communicated to these 57,000 kilogrammes represents an expenditure of power employed by the motor without any useful result; and as the motor is a living one, this expense of strength represents an exhaustion, or if you like it better, a degree of fatigue, proportioned to the effort necessary for its manifestation. This calculation is most simple and readily understood. It is to be noted, nevertheless, that I have omitted a considerable fact: which is, that the weights I have tabulated are situated at the extremities of the limbs, and that the arms of the levers on which the muscles act to raise them, being infinitely shorter than those of the physiological resistance to which these weights are added, the intensity of their action ought, therefore, to be singularly increased. But to measure this intensity of action would require a mathematical aptitude which I do not possess. I will not, therefore, dwell on this point, notwithstanding its importance, and am content to signalize it. Otherwise, the figures I present speak for themselves, and tell us that the diminution in the weight of horse-shoes is not an accessory consideration, so far as the useful application of the horse's strength goes.'
It will be seen that this question of weight at the lower end of the limb is a serious one; the power moving it acting at the upper extremities, and having but short leverage. We can readily imagine what a difference in power must be required to move a pound at the fore-arm or knee, and at the lower surface of the foot, and how much the lightening of a shoe by one or two ounces must affect the motion of the limb.
In shoeing, this important consideration has been
