Lanterna Rally

Author: Baron Edmund Beckett Grimthorpe

Publisher: Theclassics.Us

Published: 2013-09

Total Pages: 68

ISBN-13: 9781230256276

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1850 edition. Excerpt: ...to the planes of the rest of the wheels. Such clocks have of course the advantage of being portable, and are called carnage clocks. But unless they have compensated balances, they are much more affected by changes of temperature than pendulum clocks, or watches, which are kept at a pretty uniform temperature by being carried in the pocket, as will be explained in 124. 112. If you take a common spring clock, with its wheels and escapement arranged exactly like that of which a drawing was given at p. 49, and instead of the crutch for the pendulum put a wheel of the nature of a fly-wheel, this will be very nearly a watch. Not quite, however; for it still differs from a watch in this, that the fly-wheel or balance has no spring, and so its vibrations will depend only upon its own moment of inertia, and the force of the train. And this last dependence is just what we want to get rid of, or to compensate in such a way that comparatively large vibrations of the balance shall be performed in the same time as smaller ones. Dr. Hooke ascertained, among his numerous other discoveries and inventions, that the vibrations of a spring in large or small arcs are very nearly isochronous. The reason of which is that the force with which a spring endeavours to resume its position generally varies as the angle through which it is bent, with the exception before mentioned in 80; and a body acted upon by such a force as this (as a pendulum moving in a cycloid is) must oscillate through any distance in the same time. Consequently if one end of a spiral spring is fixed to the frame in which the balance-arbor turns, and the other to the balance itself, in such a position that when the spring is at rest the pallets stand half way between each beat, ...