ROME' DE L'ISLE, JOHN BAPTIST LOUIS, a cele brated French crystallographer, was born at Gray, in Pranche•Comte, in 1736. At a very early period of his life he went to India, as secretary to a corps of en gineers. The period of his return is not known, but in 1757 he went a second time to the east, was taken prisoner at Pondicherry, and finally returned to Europe in 1764, after a captivity of five years endurance. In 1766 he published a " Letter to M. Bertrand, on Fresh Water Polypes," in which he considered the polypus as a tube for the reception of an infinity of small isolat ed animals. Having begun the study of natural histo ry, along with Le Sage, he directed his particular at tention to mineralogy. His first work was a Catalogue Raisonnee of M. Davila's collection, intended for sale, which appeared in 1767, in three volumes, 8vo.; and he was thus led to an accurate examination of the forms of crystallized bodies, and to the construction of a sys tem of crystallography. His first essay on crystallo graphy was published in 1771, and contains 110 species of crystals, of which Linnaeus knew only about 40. His fame was rapidly extended by this production. Lin naeus courted his correspondence, and he was honour ed with a seat in many of the academies of Europe.— His countrymen, however, were the last to appreciate his talents, and from the circumstances of his having published eight explanatory catahigues of collections from 1767 till 1782, they were disposed to regard him more as a scientific drudge than as a philosopher. In 1778 he published an explanation of Le Sage's theory of chemistry, and in 1779 appeared his work entitled L'..detion de Feu central, banni de la Surface du Globe, et le Soleil retabli dans ses droits. His first work, how ever, by which he will he long remembered, was pub lished in 1783, under the title of Crystallographic; ou Description des Formes propres de tous les Corps du Regne Illinerale, in four volumes octavo.
Besides the works now mentioned he published. CharacOres Extericures des illineraux, in 1787, and in 1789, Illitrologie; ou Tables pour servir a l' Intelli gence des Poids et des Illesures des .4nciens, d'apres leura rapport avec les Poids et les Illesures de la France.
Some time before his death, the eyes of our author failed him, and he died of a dropsy at Paris, on the 10th March, 1790.
The great merits of Rome de l'Isle in mineralogy are less generally acknowledged than they deserve; particularly by the French mineralogists. Modern mi neralogists are often astonished at the accuracy of the description given by this author, even of such sub stances as were afterwards confounded with each other by Flatly and those who copied him. In almost every page the power of observation is displayed in a remarkable degree, joined with good sense, correct reasoning, and a vast mineralogical erudition. His fi
gures of crystals, indeed, are frequently far from af fording the pleasing effect of geometrical perfection, which captivates the eye in the figures adorning the great work of flatly; yet they betray the hand of the master, who seized the peculiar character of the indi vidual crystals which he represents, and which is often better preserved in these sketches than in better execu ted drawings.
The student will always find a great deal of instruc tion in perusing the second edition of his Crystallogra phie, the result of more than twenty years continued and well-directed exertions; but those who are already proficient in the science will find pleasure in discover ing in his writings that they have often been antici pated in their descriptions. It may be said with perfect propriety, that, however ingenious the views of Haiiy may have been in regard to the property of cleavage, he could never have succeeded in establishing them as a general system, applicable to all crystalized mine rals, had he not possessed the observations and draw ings of Rome de l'Isle. This great man met with all the opposition commonly incidental to new ideas, or to a degree of accuracy which, in fact, is far beyond what had been customary before; but the prejudices had worn off, when Haiiy's system appeared, which then earned the rewards both of its own merits and of Rome de l'Isle's. Haiiy has always been candid enough to acknowledge every thing he owed to the latter; he supplied the link which made Rome de l'Isle's observations useful, by introducing general views in crystallography, founded upon geometrical processes, and by giving a particular name to every substance determined as a particular species. Rome de l'Isle was particularly regardless of the two great points, which, according to Linnaeus, like the thread of Ariad ne, lead us through the mazeof the variety of nature,— the systematic disposition and denomination of the species; although in his paper Des Caraea-res Exte rieures des Mineraux, he has given principles for the determination of the latter, independent of chemical analysis, which will stand every attack, and remain one of the most valuable disquisitions on the subject ever proposed to the public, and which ought to be studied by every one who wishes to inform himself on this important subject. Rome de was the first to vindicate mineralogy to the province of natural history; against the pretensions of chemists, who, even at that time, when chemical knowledge, particu larly of minerals, was so imperfect, undervalued every thing that was constant in minerals. This may ac count, in a great measure, together with the neglect of those parts which have been afterwards so highly improved by Haiiy, why Rome de l'Isle's works have never had that degree of influence to which they were entitled by their excellence.