chemists were imprisoned, in the hope of forcing them to make gold.

Fortunately we were no longer in the 12th century; the King, to whom M. Duhamel's friends were obliged to make direct plication, gave him all justice, and the circumstance having recalled him to the remembrance of the minister, contributed in the end to his withdrawing himself from the precarious situation to which he had been reduced.

In 1775, he was named commissary of the council for the inspection of forges and furnaces, which opened up anew the path to employment. However, he always regretted that this event broke up his plans with regard to the barren grounds, so firmly persuaded was he that they would not only be a new source of public prosperity, but also a certain basis to his own private fortune.

While he was connected with his great foundery, he had begun to make known his own discoveries and observations. In 1772, he made a journey to the Pyrenees, and shewed the advantages of the Catalonian method of manufacturing iron, and the possibility of applying it to the mines of the interior of the kingdom. It is well known that this method consists in making the ore pass immediately into a state of semi-fluidity, in a crucible, where it is preserved from the contact of air, and in submitting it immediately after to the action of the hammer. In this manner the great outlay required for the construction of furnaces is saved, much fuel is economised, and less is lost by combustion; the iron is separated and refined in the same crucible, and by a single operation. To prove that the rock ores of the Pyrenees were not the only kinds that might be thus treated, he had ores transported from the Angoumois and reduced at the Pyrenees. The operation succeeded perfectly.

Once free from all engagements with individuals, he set no bounds to his zeal, and his writings and experiments became more numerous. In 1775, he visited the mines of Huelgoat in Lower Bretagne, and discovered to the great benefit of the proprietors, that a substance of an earthy appearance, which they rejected as useless, was very rich in lead and silver. In 1777, he improved the forges in the same country, as well

as the founderies of carron and iron balls at Lanoue, and published, as we have already mentioned, his secret with respect to the cementation of steel.

In 1779, he projected great improvements in the refining of silver, that is to say in the art of separating that metal from copper by means of lead. In 1783, he invented an instrument calculated for following better the direction of veins, and for determining the points at which they cross. In 1784 especially, the period of a great competition for a place in the Academy, he presented still more numerous memoirs than formerly. He furnished a means of extracting metal from the poorest galenas; taught how to treat without loss the ores rich in iron, by adding to them in suitable proportions earths calculated to produce a sufficient laitier, and thus prevent their combustion; shewed that most of the scoriæ of lead may still be turned to account; and pointed out the surest means of extracting gold and silver from goldsmith's ashes.

These last works procured him successively in the Academy the places of correspondent and associate, and at length obtained for him from the government the recompense so long promised to his first efforts.

The minister of Louis XVI. resumed the old projects of M. Trudaine. In 1781, M. Necker laid the first foundation of their realization, and, in 1783, M. de Calonne completed it. A school of mines was established at Paris, and after more than twenty years expectation, M. Duhamel was nominated to the chair of mining and metallurgy.

Undertaking such an office was devoting himself somewhat late to an occupation for which he was designed from his youth, and which should have been commenced with the active vigour of that age. Not only was it difficult for M. Duhamel to acquire all of a sudden the elocution which could alone fix the attention of his pupils; he had also to learn in detail the theories whose progress the exercise of art, and a life passed in forges and manufactories had not permitted him to follow, and to enter anew upon the meditations necessary for arranging them so as that they might be brought forward in a manner worthy of his office. He had to inform himself in short of all that science

and time had recently added to the art. His devotion to his duties, and his love to his pupils, supplied all; from the beginning he shewed himself worthy of his situation, and during the thirty years he filled it, the affection and gratitude of those whom he taught continually rewarded his labours. The 'gratitude of many others also was due to him, could he have reclaimed it from all those whom he has enriched.

In fact, if it be desired to know what effect a well arranged institution, however inconsiderable it may be, what a public professorship, for example, may produce in a great kingdom, let it be considered what our mines then were, and what they have since become. Our workings of iron and coal are quadrupled; the iron mines which have been opened near the Loire, in the coal district, and in the midst of fuel, will produce metal at the same price as in England. Antimony and manganese, which we formerly imported, we now export largely. Chrome, which was discovered by one of our chemists, is also now the very useful production of one of our mines. Already very fine tin has been extracted from the mines of the coast of Bretagne. Alum and vitriol, formerly unknown in France, are collected there in abundance. An immense deposit of rock-salt has lately been discovered in Lorraine, and there is every reason to believe that these operations will not stop there. It is not undoubtedly to a single individual, nor to the erection of a single chair, that all this good can be attributed; but it is not the less true, that this man and this chair gave the first impulse.

It was for his pupils that M. Duhamel composed his principal work, of which a volume appeared in 1787, under the title of Geometrie souterraine.

It is well known that the metals, and especially the more precious metals, have not been distributed by nature in homogeneous and extended masses. Dispersed in small parcels among rocks, it is only by great labour that man has been able to become possessed of them. Nor have they anywhere been scattered at random. Their position, like all the other relations of natural objects to each other, is subjected to laws. It might be said that the oldest mountains have been broken or split to afford them asylums. Those immense fissures which traverse rocks in all directions,

look as if they had been subsequently filled with the foreign materials at the bases of the mountain, and it is in the intervals of these foreign rocks, in these veins, that the precious molecules, often of very varied composition, are deposited. From them the successive discoveries of chemistry have enabled us to extract the metals in their pure state.

The art of the miner consists in discovering principal veins, in following them, in finding them again when they are interrupted, in allowing none of the accessory veins which may intersect them to escape; lastly, in raising all the parts that may contain metal, and in raising none else. He must therefore know the general laws of the distribution of veins, of their inflections and intersections; and when he has wrought out a part, when he has perforated the mountain in every direction in which veins have presented themselves to him; when he has scooped out a second time this labyrinth, which seems to have existed since the original disruption of the rocks, and before the substances which fill up the fissures were deposited; he must be able at all times to find his way through those gloomy recesses, he must even retain an accurate knowledge of the galleries, of the veins which he has abandoned, that he may not be annoyed by the waters, on coming imprudently upon them again by a different route.

Such is the object of subterranean geometry; it finds out the direction of the veins toward the cardinal points, and their inclination to the horizon; it fixes the three dimensions of the works; it follows them, and verities their progress by clear and distinct images. Its means are such as they might be in those narrow cavities, where the view extends only a few feet, and where the light of day does not penetrate. Some lamps, a compass, and an instrument to measure the inclination, are all that can be used. It cannot, like common geodesy, either connect its operations with those of astronomy, or establish great triangles, to rectify its small errors. It therefore requires particular methods, which supply by their accuracy of detail those grand means of rectification; and these methods must be such as men of the class who pass their melancholy lives in those depths, may comprehend and execute with sufficient accuracy.

These operations are what M. Duhamel teaches in his book.

It is not a work of an elevated order of geometry, nor one that had the pretension of offering new mathematical truths: it is a purely practical treatise, a sort of surveying of a particular kind, but which the art of mining could want, and which every miner would have been obliged to make out for himself, had not the author spared him the trouble. This work is at the present day the manual of all who practise the art of mining in France; and as if the light of improved science ought to reflect toward the focus from which it had issued, it has been translated into German, and is very generally diffused among the miners of that country.

In the subsequent part of his work, M. Duhamel intended to treat of the other processes of the art, of the various modes of digging, incasing, walling, ventilating, and drying mines, of transporting the ore, picking, washing, stamping, melting, and refining it. The police of mines, their administration, the questions of law which refer to them, and the regulations to which they are subjected in different countries, were equally to be explained. But the events which involved the country in confusion a short time after the publication of his first volume, arrested the progress of the work, and we can form no idea of it excepting from the fragments which he has inserted in the Encyclopedie Methodique.

During these events, M. Duhamel himself was much distressed; but he acted as on all other occsions, he took precautions without complaining. At the first appearance of danger, he purchased some lands in America, and formed the resolution of carrying his talents to that country.

When on the point of embarking, he still granted some moments to the tears of his family: but in the few days which this delay occupied, the men who menaced every kind of merit were thrust down, and immediately the proposals of the government, which had been restored to some degree of moderation, fixed him anew in his country. After this period, he discharged the duties of professor and inspector-general of mines, and in the latter quality performed important missions, always with zeal, and always without ostentation. At length his age, and loss of strength, forced him in 1811 to retire. He was then 81 years old. The remaining part of his life was passed in calm re