an instrument for ascertaining the relative strength of men and horses. An ingenious instrument of this kind was invented in London about the middle of the last century by the celebrated mechanician Graham, and improved by Desaguliers. It was constructed of woodwork however, and was soon found to be too complicated and cumbersome to be of any general utility. A simpler instrument was that invented by Leroy of the French Academy. It consisted of a metal tube ten or twelve inches in length, placed vertically on a foot like that of a candlestick, and containing in the inside a spiral spring, having above it a graduated shank terminating in a globe. This shank, together with the spring, sunk into the tube in proportion to the weight acting upon it, and thus pointed out, in degrees, the strength of the person who pressed on the ball with his hand. Simpler and more ingenious than either of these however is that of Régnier, of which a detailed description will be found in the Journal de l'Ecole Polytechnique, tom. ii.

This dynamometer, in its form and size, has a near resemblance to a common gramometer. It consists of a spring twelve inches in length, bent into the form of an ellipse; from the middle of which arises a semicircular piece of brass, having engraved upon it the different degrees that express a force of the power acting on the spring. The whole of this machine, which weighs only two pounds and a half, opposes, however, more resistance than may be necessary to determine the action of the strongest and most robust horse.