ROLLERS

The name given by seamen to unusually heavy waves, which set in upon a coast or island without wind. They are freouent at Ascension. ROLLING, in Mechanics, is when all the parts of the surface of one bcxly come into succe ive contact with those of another, and under such conditions as that at every instant the portion of the two surfaces which have been in contact are exactly equal. When this condition is not fulfilled, the one surface is said to slide upon the other. The friction of bodies in rolling is much le than in that of sliding; and hence the advantage of wheels to all kinds of carriages. See Fuiotion. Rolling. In Naval language, the lateral oscillation J0G2 I ROMAN CATHOLICS. of a ve el. This motion, which is* often very great when the ve el is running before the soa, endangers the masts, strains the sides, and loosens the decks at the waterways; it is also liable to cause the guns to break adrift. When the centre of gravity is too low, the oscillations begin and end violently. The changes in the stowage nece ary to modify the nature or extent of the roll are made by seamen from experimental knowledge. [s. 1075]