The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 Chap. XL.] DYNAMOMETERS. 489 velocity of 32'1889 feet ; and we have seen that force, can be measured by the velocity produced in unit mass in unit time. So that the gravitation measurement can become absolute measure. At London, the pound weight produces 32-1889 units of force. It is to be noted that the action of gravity differs in amount in different places (page 504), so th
The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 Chap. XL.] DYNAMOMETERS. 489 velocity of 32'1889 feet ; and we have seen that force, can be measured by the velocity produced in unit mass in unit time. So that the gravitation measurement can become absolute measure. At London, the pound weight produces 32-1889 units of force. It is to be noted that the action of gravity differs in amount in different places (page 504), so that for the same body the force differs at different parts of the earth's surface. Dynamometers are instruments for measuring forces in pounds or kilogrs. Fig. 199 shows one form. It consists of two steel arcs AB and CD, connected together at the extremities. The in- strument is suspended by the ring R, and a weight is at- tached to the opposite hook. The curves of the arcs are increased by the weight, the action being resisted by the Fig-. 199.—Dynamometer, elasticity of the steel. The «/ amount by which the arcs are separated in the middle is measured by the graduated bars, one being attached to the middle of each arc. The bars slide on one another, and are graduated by hanging on various known weights, which mark the extent of separation effected. An unknown force can then be estimated in terms of the previous graduation. Another form of the same instrument is made for estimating force exerted not by traction, but by pres- sure. For instance, such a form is made for estimating the pressure that can be exerted by the hand in squeezing. The instrument is grasped in the hand and the arcs pressed together. Between the arcp is a dial plate and an indicator, which travels a greater or less distance over the dial plate according to the pressure
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