modern poetry, denotes a rest or pause so introduced as to aid the recital, and render the versification more melodious. It divides a verse or line into equal or unequal parts.

Ceteris Paribus, a Latin term in frequent use among mathematical and physical writers. The words literally signify other things being alike or equal. Thus we say, the heavier the bullet, ceteris paribus, the greater the range; that is, by how much the bullet is heavier, if the length and diameter of the piece and strength of the powder be the same, by so much will the utmost range or distance of a piece of ordnance be the greater. Thus also we say, the velocity and quantity circulating in a given time through any section of an artery will, ceteris paribus, be according to its diameter, and nearness to or distance from the heart.

caffa. See Kaffa.

Caffeine, the stimulant principle in coffee, was discovered by Runge in 1820. He obtained it by precipitating a cold infusion of coffee by acetate of lead, and throwing down the lead by sulphuretted hydrogen. It was obtained in colourless acicular crystals. It contains 21.6 per cent of nitrogen, a larger quantity of that gas than is yielded by any other organic compound except urea and uric acid. Caffeine is identical in composition with theine. See Chemistry.