HAUY, Rene , Just, a celebrated mineralogist, was born at St Just, a small country town of France, in the department of the Oise, on the 28th of February 1743. He had a younger brother, who became celebrated as the inventor of a method of instructing the blind. Their father was a small linen manufacturer, and his means were so slender, that but for the generosity of others, it is doubtful if his children would ever have learned any other profession than his own. Early in life the subject of this memoir evinced a singularly pious disposition; and from this circumstance arose the improvement of his fortune. Whilst yet a mere child, he took remarkable pleasure in religious ceremonies, especially in church music, a taste for which was blended with his devotional feelings. His regular attendance at church service attracted the attention of a prior, who placed the youthful devotee under the care of some monks, for the purpose of instructing him; and under their tuition he made so rapid progress, that his mother was induced to take him to Paris to complete his studies. Her means were scarcely sufficient to enable her to live a few months in the capital; but she preferred submitting to severe privations rather than relinquish the hopes which she had cherished respecting her son. For some time, young Haiiy held the humble situation of a singing boy in a church, and by this means he gained a subsistence, limited indeed., but sufficient for him whose wants were so few and whose ardour was so great, whilst he also gratified his propensity for music. By the influence of his protectors at St Just, he at length procured a bursary in the college of Navarre, where he was enabled to prosecute his studies without interruption. His application and good conduct procured him the esteem of his superiors; and when the period of his probation as a scholar had terminated, he became a teacher in the establishment. He took his degrees, and commenced teaching at twentý-one years of age. Some time afterwards he was appointed preceptor to a higher class, and to this humble but honourable office his ambition seems to have been limited. His leisure hours were occupied in the study of botany; but by a fortunate accident his attention was withdrawn from plants to examine the structure of minerals. His mind had for some time been filled with ideas relative to the contrast presented by the vegetable and mineral kingdoms, inasmuch as in the complicated forms of flowers, fruits, and other organised bodies, a never-failing unity of form pertained to each individual plant or herb, whilst the same stone or salt, without its composition being changed in the slightest degree, exhibited itself in cubes, prisms, and other shapes. Occupied with these reflections, he accidentally dropt from his hand a beautiful specimen of calcareous spar, crystallized in prisms, one of which was broken in such a manner as to present a new crystal, differing in form from the prism, but having the surfaces not less smooth. On examination, the inclinations and angles were found to be similar to the rhomboid crystals of Iceland spar. He further examined pieces of spar crystallized in other forms, and he still found the same rhomboid which had first struck him, the fragments which fell from it being also small rhomboids. The importance of the discovery at once flashed upon his mind, and, like Archimedes starting from the bath, he exclaimed, “All is found.” The important conclusion at which he arrived was simply this, that the molecules, or, as it were, component parts, of calcareous spar, have invariably the same geometrical figure; the variety of external forms which the masses assume arising from the manner in which the smaller crystals composing it are arranged. By examining a number of substances, Haüy completely established the fact that this was a law of nature which obtained universally. Each mineral was found to have identical constituent molecules, a nucleus always similar to itself, and laminae, or accessory layers, producing all the varieties of external form.

Another condition, however, was to be fulfilled before the theory could be admitted as certain. If the nucleus and constituent molecule have each a certain invariable form, geometrically determinable in its angles, and in the relations of its lines, each law of decrement ought also to produce determinable secondary faces; and likewise, when the nucleus and the molecules are once given, the angles and lines of all the secondary faces which the decrements would produce, should be susceptible of calculation beforehand. Before Haüy could accomplish this, however, he required to study geometry, which he had almost forgotten. This he quickly learned, and having invented a method of measuring and describing the forms of crystals, he established beyond all doubt the true law of crystallization. This subject is treated of at length in the article Crystallization.

Haüy first made known his discoveries to his master Μ. Daubenton, by whom they were communicated to the celebrated Laplace. The young philosopher received the most flattering invitations to join the academy, but' his modesty for some time kept him back. His scruples, however, having been at length overcome, he, on the 10th of January 1781, read his first memoir, in which he treated of the garnets and of calcareous spars. The members of the academy showed great eagerness to acquire him; and, on the 12th of February 1783, he was elected to the situation of adjunct in the botanical class, in preference to several learned botanists, who were candidates for the honour. His new colleagues bore flattering testimony to his merits, by requesting him to give oral explanations and demonstrations of his theory; and be also read a course of lectures on the subject, at which were present the most distinguished French philosophers of the day. The modes of calculation which he had invented, and the formulae he employed, representing all the possible combinations of crystallography, will be found in the volumes of the academy for 1788 and 1789.

Objections were started to the theory of Μ. Haüy; but the only reply which he made to them consisted in more extended researches, and a more ample induction of facts. He also applied his principle in a new and remarkable manner to the discovery of the composition of minerals. If, reasoned he, each substance has a characteristic nucleus and constituent molecule, then the component parts of minerals, whose composition is unknown, may be discovered by the form of their crystals; and thus a new and powerful instrument of analysis may be employed in mineralogical and chemical investigations. His practical researches established the correctness of the conclusions at. which he had arrived. At this time the most distinguished mineralogists confounded under the name of [7:11:170]schorl a number of minerals, which, although possessing some characteristics in common, did not bear so remarkable a resemblance to one another as to warrant their being classified together as belonging to the same species. M. Haiiy, therefore, suspecting that distinctive differences existed amongst them, commenced a series of experiments conducted on his own principle. He mechanically divided the substance called white schorl, and found in it the nucleus and molecule of felspar. By chemical analysis, it was found to be actually one of the felspars. Encouraged by his success, he continued his researches, and discovered amongst the schorls no less than fourteen species. From this moment Μ. Haiiy ceased to be a mere experimenter in physics, and stood prominently forward as the great legislator of mineralogy. A new era in the science dates from the period of these researches; and, by the study of the crystalline structure of minerals, each year has produced some unexpected discovery.

It is, or at least was, a regulation in the university with which Μ. Haiiy was connected, that when a professor had served twenty years, he was entitled to a retiring pension. With this, joined to the produce of a small benefice, although barely sufficient for his wants, he resolved to retire from public duty, and devote himself wholly to philosophical pursuits. His designs, however, were frustrated by the breaking out of the Revolution. After the overthrow of the monarchy, one of the first measures taken by the democratical party was the imprisonment of the priests; and Μ. Haiiy, being naturally identified with them on account of his scrupulous piety, became a participator in their sufferings. He was surprised in his humble retreat by a body of armed men, who rudely demanded if he had any fire-arms. ' None but these, said he, drawing a spark from his electrical machine. This for a moment disarmed the intruders, but only for a moment. Fortunately, however, he did not share the fate of Archimedes. They spared his life, but he was ultimately thrown into prison. His confinement, however, was of short duration. The members of the academy, and other influential individuals, so interested themselves in his behalf, that they procured his deliverance just the day before the massacres of September. From this period he was no more disturbed, although, as a priest, he continued to perform his sacerdotal functions daily, and had even the courage to write in behalf of some individuals, amongst whom was the celebrated Lavoisier, who had been arrested by order of the Convention.

At the cabinet of the Conseil des Mines, and by the aid of that administration, Μ. Haüy prepared for the press his celebrated work on mineralogy, which appeared in 1801, in four vols. 8vo, with a quarto volume of plates. “This book,” says Cuvier, “possesses in the highest degree two advantages which are very rarely found combined; the first of which is, that it is founded upon an original discovery, entirely resulting from the genius of the author; the second, that this discovery is folĮowed out in it, and applied with incredible perseverance even to the varieties of minerals. Every thing is grand in the plan, precise and rigorous in the details; it is completed like the doctrine itself of which it contains the exposition.”

In his determinations of mineral species, Μ. Haüy gave the chief rank to crystallization, although of course it was never intended by the author that chemical analysis should be neglected. He only maintained that it was inadequate to the determination of their species, “because,” observes Cuvier, “it has no sure means of distinguishing the accidental from the essential substances; because it is not in a condition, with respect to certain classes of stones, to affirm that it knows their elements; and because it every day discovers elements which were previously concealed from it.” - By his indefatigable industry, Μ. Haüy determined the nucleus and molecules, with the measure of their angles, and the proportion of their sides, of almost every crystallized mineral at present known. In a word, he may be said to have placed mineralogy amongst the precise and methodical sciences, and to have done for it what Newton did for astronomy. On the demise of the professor of mineralogy to the Museum of Natural History, Dolomieu was promoted to the chair in preference to Μ. Haüy. But imprisonment, and afterwards a premature death, prevented that individual from occupying the chair; and on the 9th of December 1802, Haüy was appointed to the vacant professorship. A new life was now infused into the mineralogical department. Large additions were made to the collections, and every thing was arranged in the most perfect order, according to his own principles of classification. To the students he showed the utmost condescension and kindness, conversing familiarly with them, and even taking them to his own house, and opening up his private collections to their inspection. When the university was founded, Haüy’s name was placed on the list of one of its faculties. Lectures were not expected from him; but, unwilling to bear a title without fulfilling its duties, he made the pupils of the normal school come to him; and, in conversation, he communicated to them his discoveries. By order of the government, he drew up a treatise on physics for the colleges. He had previously established a claim to be employed in the execution of such a work, by the ingenious manner in which he had applied physics to mineralogy, by the publication of several interesting memoirs on the electricity and double refraction of minerals, by his elegant exposition of Aepinus’s theory respecting electricity and magnetism, and by the success which had attended a course of physics delivered by him at the normal school instituted in 1795 by the Convention, and which lasted only a few months. He was averse, however, to abandon his favourite mineralogical researches; and it was only after much hesitation that he consented to undertake the task. The treatise added little to his scientific reputation, but it did no injury to his literary fame. The same clearness and purity of style for which his Mineralogy was distinguished characterise this little work. It is calculated to inspire into the young a taste for the natural sciences, and it has passed through several editions.

Μ. Haüy was repeatedly urged to communicate to government what he wished to be done for him; and when he consented to petition, his humble request was, that things might be arranged so as to bring his family near him, in order that he might enjoy their society, as the solace of his old age and infirmities. Napoleon instantly complied with his wishes, by conferring a place upon the husband of his niece. The emperor likewise granted him a pension, and, on his return from Elba, decorated the crystallographer with the cross of the legion of honour. This was alike honourable to both parties, for Haüy had opposed the assumption of the imperial dignity by Napoleon. When the subsequent changes in the French government took place, the husband of Μ. Haüy’s niece lost his situation; and he himself, when no longer capable of active exertion, was deprived of his well-merited pension. To add to his perplexities, his brother, who had gone to Russia for the purpose of gaining information relative to the instruction of the blind, returned without attaining his object, and with a constitution so completely broken, that he became a charge to his family. Thus, in his old age, Μ. Haüy was reduced to the extreme indigence which had been his lot during the early part of his career. A compensation, however, was afforded him in the kind attentions of his friends, and in the applause of Europe; whilst the enlightened of all ranks who visited Paris paid their respects to him. But these flatteries never corrupted the simplicity of his manners, and his benevolence continued conspicuous to the [7:11:171]close of his life. Notwithstanding his feebleness, he attained the age of seventy-nine, having died on the 3d of June 1823.

The intellectual powers of Μ. Haiiy are sufficiently attested by his works. In his moral character he was sincerely pious, and eminently benevolent. He seems to have regarded wealth only as the means of gratifying those sentiments of benevolence with which he was penetrated; and although the most beautiful gems of Europe passed under his review, they were by him considered valuable only as crystals which illustrated his theory. The works of Μ. Haüy are as follow :—1. Essai d’une Théorie sur la Structure des Cristaux, 1784, in 8vo; 2. Exposition raisonnée de la Théorie de l’Electricité et du Magnétisme, d’après les Principes d’Aepinus, 1787, in 8vo; 3. De la Structure considérée comme Caractère Distinctif des Minéraux, 1793, in 8vo; 4. Exposition abrégée de la Théorie de la Structure des Cristaux, 1793, in 8vo; 5. Extrait d’un Traité Elémentaire de Minéralogie, 1797, in 8vo; 6. Traité de Minéralogie, 1802, 4 vols. in 8vo, et planches in 4to; 7. Traité Elémentaire de Physique, 1803, in 12mo, deuxième edition, in 1806, 2 vols. 8vo; 8. Tableau Comparatif des Résultats de la Cristallographie, et de l’Analyse Chimique relativement à la Classification des Minéraux; 9. Traité les Pierres Précieuses, 1817, in 8vo; 10. Traité de Cristallographie, 1822, 2 vols. with engravings. Μ. Haüy also contributed papers to various scientific journals, particularly the Journal d’Histoire Naturelle, Annales de Chimie, the Journal de Physique, the Magasin Encyclopédique, the Annales du Muséum d’Histoire Naturelle, and the Journal des Mines. He also communicated several memoirs to various other scientific journals. (r. r. r.)