Contractile Force

or Contractility, (kontraktil.) [ Same der iv.] (Phys.) That property or power inherent in certain elastic bodies, on account of which, after having been extended, they reduce themselves again to their former dimensions, if permitted to do 80. It has been calculated from Joule's data that the force exerted by heat in expanding a pound of iron between 0 and 1000 during which it increases about 1 많이of its bulk, is equal to 16,000 foot pounds; that is, it could raise a weight of7 tons through a height of one foot. An application of this contractile force is seen in the mode of securing the tires on wheels. The tire being made red-hot, and thus considerably expanded, is placed on the circumference of the wheel and then cooled. The tire, when cold, embraces the wheel with such force as not only to secure itself on the rim, but also to pre home the joints of the spokes into the felloes and nave. [s. 223]