iod, to earn a quarter of
wheat required 48, a quarter of rye 32, and a quarter of barley 29
days' labour.

CORN-SALAD, or LAMB'S LETTUCE, _Valerianella olitoria_ (natural order
Valerianaceae), a weedy annual, native of southern Europe, but
naturalized in cornfields in central Europe, and not infrequent in
Britain. In France it is used in salads during winter and spring as a
substitute for lettuces, but it is less esteemed in England. The plant
is raised from seed sown on a bed or border of light rich earth, and
should be weeded and watered, as occasion requires, till winter, when it
should be protected with long litter during severe frost. The largest
plants should be drawn for use in succession. Sowing may be made every
two or three weeks from the beginning of August till October, and again
in March, if required in the latter part of the spring. The sorts
principally grown are the Round-leaved and the Italian; the last is a
distinct species, _Valerianella eriocarpa_.

CORNU, MARIE ALFRED (1841-1902), French physicist, was born at Orleans
on the 6th of March 1841, and after being educated at the Ecole
Polytechnique and the Ecole des Mines, became in 1867 professor of
experimental physics in the former institution, where he remained
throughout his life. Although he made various excursions into other
branches of physical science, undertaking, for example, with J. B. A.
Bailie about 1870 a repetition of Cavendish's experiment for determining
the mean density of the earth, his original work was mainly concerned
with optics and spectroscopy. In particular he carried out a classical
redetermination of the velocity of light by A. H. L. Fizeau's method,
introducing various improvements in the apparatus, which added greatly
to the accuracy of the results. This achievement won for him, in 1878,
the _prix Lacaze_ and membership of the Academy of Sciences in France,
and the Rumford medal of the Royal Society in England. In 1899, at the
jubilee commemoration of Sir George Stokes, he was Rede lecturer at
Cambridge, his subject being the undulatory theory of light and its
influence on modern physics; and on that occasion the honorary degree of
D.Sc. was conferred on him by the university. He died at Paris on the
11th of April 1902.

CORNU COPIAE, later CORNUCOPIA ("horn of plenty"), a horn; generally
twisted, filled with fruit and flowers, or an ornament representing it.
It was used as a symbol of prosper