This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874 edition. Excerpt: ...for wind and weight outside, there being another of cast iron inside the clock room, to divide the pressure between the two ends of the arbor. This copper tube of each minute hand only weighs about 28 lbs., though they are q4 in. wide near the centre, running off to 5 in. at the end; the gun-metal stalk of each hand weighs very nearly 1 cwt.; but the whole of that weight is near the centre, and' so its moment of inertia at each beat of the pendulum affects the clock very much less than if the same weight were distributed all along the hand. It is remarkable that from the momentum of the hands, and the general elasticity of the leading off rods, they move continuously, and with no visible jump as usual. The length of each hand and its external counterpoise is 14 feet; and the total weight of each hand with its external and internal counterpoises is now within 2 cwt., whereas Sir C. Barry's 4 minute hands and counterpoises (of which I shall have to speak in the history of the clock) weighed a ton and a quarter. His hour hands are still there; for though verybad in construction and three times as heavy as they need be, their motion is so slow that they do not sensibly affect the clock as the minute hands did, and so they may as well stay until they become unsafe. One of them cracked and had to be taken off. The hour hand arbor is a tube 5 inches wide, and lies on large friction rollers both behind the dial and within the clock room. It was easy enough to put the clock room end of the minute hand arbor on friction rollers too, as it of course projects beyond the other; but at the other end it is managed by setting the pivots of 4 smaller rollers in a pair of rings screwed outside the hour hand tube, and cutting holes in that for the rollers to go...