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. 1851 edition. Excerpt: ... weather, according as the piece of catgut which is attached to them stretches or contracts. How can it be proved that metals expand by heat, and wood by moisture?--An iron bar, when heated, cannot be made to enter an opening which, when cold, it will readily enter. The gate of an iron railing which in cold weather will shut and open easily will sometimes stick fast on a warm day, on account of there being a greater expansion in it and the neighbouring railing than of the earth in which they are fixed. For the same reason the centre arches of iron bridges are higher in hot weather than they are in cold weather; a property forgotten to be noticed by the architect in the erection of Southwark cast-iron bridge, which oversight occasioned great damage to the bridge, as the extreme variations of atmospheric temperature occasioned a difference of height in the arches at different seasons amounting to about one inch. The same principle extends to many metallic instruments, as the pendulums of clocks, the balance-wheels of watches, &c. they being affected by the change of seasons and their removal to a warmer or a colder climate. By the same cause also musical instruments are out of tune, the expansion of the strings being greater than that of the wooden frame-work of the instrument. The reason that wooden gates stick fast in wet weather is, that they are more swelled with the wet than the earth is on which they stand. # The change or variation produced in bulk to wood and metals by the vicissitudes of temperature is not peculiar to them; for all solid bodies are subject to the same change of magnitude from the same cause. When the weather is cool they shrink and contract their dimensions, but when the temperature of the weather increases their...