the number of 789) contain investigations on the theory of series
(where he developed with perspicuous skill the notion of convergency),
on the theory of numbers and complex quantities, the theory of groups
and substitutions, the theory of functions, differential equations
and determinants. He clarified the principles of the calculus by
developing them with the aid of limits and continuity, and was the
first to prove Taylor's theorem rigorously, establishing his
well-known form of the remainder. In mechanics, he made many
researches, substituting the notion of the continuity of geometrical
displacements for the principle of the continuity of matter. In
optics, he developed the wave theory, and his name is associated with
the simple dispersion formula. In elasticity, he originated the theory
of stress, and his results are nearly as valuable as those of S.D.
Poisson. His collected works, _OEuvres completes d'Augustin Cauchy_,
have been published in 27 volumes.

See C.A. Valson, _Le Baron Augustin Cauchy: sa vie et ses travaux_
(Paris, 1868).

CAUCUS, a political term used in America of a special form of party
meeting, and in Great Britain of a system of party organization. The
word originated in Boston, Massachusetts, in the early part of the 18th
century, when it was used as the name of a political club, the "Caucus"
or "Caucas" club. Here public matters were discussed, and arrangements
made for local elections and the choosing of candidates for offices. The
first mention of the club in contemporary documents occurs in the diary
of John Adams in 1763, but William Gordon (_History of the Independence
of the United States of America_, 1788) speaks of the Caucus as having
been in existence some fifty years before the time of writing (1774),
and describes the methods used for securing the election of the
candidates the club had selected. The derivation of the word has been
much disputed. It was early connected with "caulkers," and it was
supposed referred to meetings of the caulkers in the dockyard at Boston
in 1770, to protest against the action of the British troops, or with a
contemptuous allusion to the lower class of workmen frequenting the
club. This is, however, a mere guess, and does not agree with the
earlier date at which the club is known to have existed, nor with the
accounts given of it. That it was a fanciful classical name for a
convivial club, derived from the late Greek