DYNAMOMETER

(Gr. ivvotfMi, power, and f/.ir^ev, measure.) An instrument for measuring power of any kind, as the strength of men and animals, the force of machinery, the magnifying power of a telescope, . An instrument for measuring animal force was invented by Mr. Graham many years ago, and afterwards improved by Desaguliers; but as it consisted of wooden works, it was too heavy and bulky to be conveniently used for ordinary purposes. Leroy, of the Academy of Sciences of Paris, proposed a dynamometer, which consisted merely of a tube of metal of ten or twelve inches in length, placed vertically on a stand, and containing a spring in its interior, which indicated by its compre ion the amount of the force applied. This instrument was in fact the same in principle as the common spring balance. The most convenient dynamometer is that of Regnier, which is described in Cahier.5. of the Journal de VEcole Poly technique. It consists df an elliptical steel spring of about 12 inches in circumference, and the force is applied 371 DYSPEPSIA. either by pre ing the two vertices of the Axis minor against each other, or by drawing in opposite directions the two ends of the axis major. In both cases the sides of the spring are made to approach each other; and thus they move an index which marks the degree of approximation on a semicircular scale. By means of this machine the mean force is ascertained which a man can exert with the right hand, or with the left, or with both together, and in various positions of his body. Some interesting results relating to the average strength of men at diflerent ages, and of different weights and sizes, have been deduced by M. Quetelet of Bru els from numerous experiments with this cjynamometer. See Strength of Animals. DYNASTID^. {Gr.lvvoi.(rrvis, a master.) A family of beetles, including the giants of the Coleopterous order. They are remarkably powerful insects, excavating burrows in Ihe earth and in putrescent timber, upon the latter of which they principally feed. [s. 384]