DUROCHER

durocher, joseph marie elisabeth (1817-1858), french geologist, was born at rennes on the 31st of may 1817. educated at the ecole polytechnique and ecole des mines in paris, he qualified as a mining engineer. early in his career he travelled in the northern parts of europe to study the metalliferous deposits, and he contributed the articles on geology, mineralogy, metallurgy and chemistry to paul gaimard's _voyages de la commission scientifique du nord, en scandinavie, en laponie, au spitzberg et aux feroe, pendant les annees 1838-1840_. in 1844 he became professor of geology and mineralogy at rennes. his attention was now largely directed to the study of the artificial production of minerals, to the metamorphism of rocks, and to the genesis of igneous rocks. in 1857 he published his famous _essai de petrologie comparee_, in which he expressed the view that the igneous rocks have been derived from two magmas which coexist beneath the solid crust, and are respectively acid and basic. he died at rennes on the 3rd of december 1858. durra (also written _dourah_, _dhura_, &c.; arabic for a pearl, hence a grain of corn), a cereal grass, _sorghum vulgare_, extensively cultivated in tropical and semi-tropical countries, where the grain, made into bread, forms an important article of diet. in non-arabic-speaking countries it is known by other names, such as indian or african millet, pearl millet, guinea corn and kaffir corn. in india it is called jowari, jowaree, jawari, &c. (hindi, _jawari_).