DELESSE, ACHILLE ERNEST French geologist and mineralogist, was born at Metz Feb. 3, 1817, and educated at the Ecole Polytechnique and the Ecole des Mines. He was successively professor of mineralogy at Besancon, of geology in Paris, and of agriculture in Paris. In 1878 he became inspector general of mines. In early years as ingenieur des mines he investi gated and described various new minerals ; he proceeded after wards to the study of rocks, devising new methods for their de termination, and giving particular descriptions of melaphyre, ar kose, porphyry, syenite, etc. He prepared in 1858 geological and hydrological maps of Paris, with reference to the underground water, similar maps of the departments of the Seine and Seine-et Marne and an agronomic map of the Seine-et-Marne (188o), in which he showed the relation which exists between the physical and chemical characters of the soil and the geological structure. His annual Revue des progres de geologie, undertaken with the assistance (186o-65) of Auguste Laugel and afterwards (1865 78) of Albert de Lapparent, was carried on from 186o to 1880. His observations on the lithology of the deposits accumulated beneath the sea were of special interest and importance. His separate publications were : Recherches sur l'origine des roches (1865) ; Etude sur le metamorphisme des roches (1869) ; Lith ologie des mers de France et des mers principales du globe (2 vols. and atlas, 1871) . He died in Paris on March 24, 1881.