French geologist, b. at Bourges, 30 Dec., 1839; d. at Paris, 12 May, 1908. He made a brilliant course of studies at the Ecole Polytechnique in Paris, graduating there the first of his promotion, and at the School of Mines. Having been appointed mining engineer in 1864, he was chosen by Elie de Beaumont as a member of the staff entrusted with the task of drawing the geological map of France. From 1866 to 1880 he contributed, with Delesse, articles on geology to the "Annales des Mines". In 1874 he was made secretary of the committee on the submarine tunnel between England and France, and conducted the soundings with such skill that his report was pronounced most valuable and served as a basis for subsequent inquiries on the question. The French Government gave him the Cross of the Legion of Honour. Towards the end of 1875 a chair of geology and mineralogy was founded for him at the Catholic University of Paris. For a few years he occupied that position without severing his connexion with the mining department, and when the leave of absence he had obtained was cancelled (1880), he preferred to give up his official position and continue to teach a science so dear to him in an atmosphere more congenial to his religious convictions. In 1880 he was elected president of the Geological Society of France. Two years later he began to write his "Traité de Géologie", published at Paris in 1884, the style of which work was as remarkable as its contents. He treated the subject in a new way, abandoning the old methods and laying the foundation of the scientific history of the earth. Instead of confining himself to a dry description and to a mere enumeration of fossils, he ventured to make hypotheses on terrestrial dynamics, as well as on the past and present evolutions of the earth. In 1885 appeared his "Cours de Minéralogie", which gained him the presidency of the French Society of Mineralogy, and a prize from the Academy of Sciences. Not long afterwards he began at the Catholic University his lectures on physical geography, a work of such merit that he was offered the chairmanship of the central committee of the Society of Geography in 1895, and was sent to represent the society at the international congress held in London. In 1896 he published his "Leçons de Géographie Physique", a work of decided originality. Lapparent was the first to treat this subject in France, and the success of his lectures at the Catholic University, the first ever given in this department, prompted the French Government to establish a similar chair at the Sorbonne. His chief qualities as teacher consisted in the clearness and method of his treatment. He saw at once the essential points of a question and showed them in a new light. Hence the enduring success of his publications, which were many times reprinted. However deep and complicated the subject, his treatment made for simplicity. In recognition of his services to science, he was elected to the Academy of Sciences in June, 1897, and in May, 1907, when Berthelot died, de Lapparent succeeded him as secretary of that academy.
De Lapparent was not only a prolific author of original scientific works, but also, in the highest sense of the term, a remarkable "popularizer". Considering that the proper rôle of the scientist, holding by his work the closest communion with truth in this world, is to spread this truth abroad, he set forth in words perfectly simple and clear, but withal perfectly exact, the great problems of contemporary science. The style in which he did this derived an added dignity from the very simplicity in which he clothed these abstract themes. He never had recourse to that pretentious pomp of style with which ignorance is wont to mystify the lay mind. De Lapparent's writings embodied the most abstract thoughts, staightway illuminated, however, by his marvellous gift of simplification. His articles in "Le Correspondant" are masterpieces. They were always cordially welcomed, not only by the laity, but also by his colleagues in the world of science. In these articles he gave to the world in popular form his tetrahedral theory of the form of the earth, a theory as simple in principle as it was pregnant in possible applications. He also made known Brückner's curious theory of meteorological periodicity, and discussed the question of the flattening of the earth, a subject to which he succeeded in imparting much new life and significance. In this same happy style de Lapparent wrote that remarkable little work, "Some Thoughts about the Nature of the Earth's Crust", which, although based upon a series of lectures delivered by him to a lay audience, shows wonderful philosophic grasp and scientific comprehension.