(Ehrenfried Walther Von), a name well known in the republic of letters, and one of the ornaments of the last century, was born April 10, 1651, at Kissingenwald near Gorlitz in Upper Lusatia. His father was Ernest Christoph Von Tschirnhaus, Baron Kissingenwald and Stolzberg, and Oberhofenfeld, privy counsellor, and in various offices of rank under the Electors George I. and II. of Saxony, the first of whom honoured him with the distinction of the gold chain and portrait, as a mark of his sense of his merits and services. The mother of the young Von Tschirnhaus was Maria Stirling, daughter of Baron a Stirling et Achil, Stirling of Achil, or Achyle, in Scotland, an old and respectable family, as appears by an epitaph which the Duke Christian, brother of the Elector George II., inscribed on the tomb of Johan Albert Stirling of Achil, in the cathedral of Marekbourg. This gentleman had been president of the senate of the electorate, privy counsellor, director of the imposts, and master of horse to the Prince, and had, by his faithful and useful services, acquired his highest esteem.

E. W. Von Tschirnhaus was born, as has been observed, at Kissingenwald, the usual residence of the family, and possessed by it during more than 300 years. The family came originally from Bohemia, and appears to have been considerable, seeing that, from the earliest accounts of it in Lusatia, the Barons of Kissingenwald are generally found in the most respectable civil offices.

The figure which Baron Von Tschirnhaus, the subject of this relation, has made in the scientific and political world, makes it superfluous to say that his early years were well employed. Quick apprehension, a clear perception of the subject of his thoughts, and the most ardent and insatiable thirst for knowledge, distinguished him during his academical education. When 17 years of age, he was sent to Leyden. In 1672 all study was interrupted in Holland by the din of war; and Mr Von Tschirnhaus left the university for the camp. His knowledge in mathematics, mechanics, and all physical science, found ample room in the military service for shewing the importance of those sciences; and Tschirnhaus so distinguished himself by his service in this way, that Baron Niculand, a general officer of great merit, and at the same time an accomplished scholar, took delight in pushing him into every service where he could show himself and his talents.

After two years service, he returned to his father's; but finding little to interest him in the life of a mere country gentleman, and still burning with the same thirst of knowledge, he prevailed on his father to allow him to travel. His younger brother George Albrecht Von Tschirnhaus, Baron Oberhochschild, which he inherited from his grandfather Stirling, loved him with the warmest affection, and supplied him liberally with what was required for his appearance everywhere in a manner becoming his rank, and for fully gratifying his curiosity. He used often to say, "Sorry was I to lose the company of my dear brother, and I sometimes wished to accompany him; but not having his thirst for knowledge, I knew that his love for me would debar him of much happiness, which I should thus have obstructed."

Felices animae! He went to Holland, from thence into England, France, Italy, Sicily, Malta, Greece.—Returning through the Tyrol, he met his brother at Vienna, where both were in great favour at the court of Leopold. Wherever he went, he made himself acquainted with the most eminent in all departments of science, living with them all in the mutual exchange of discoveries and of kind offices. In Holland he was intimate with Huyghens and Hudde; in England, with Newton, Wallis, Halley, and Oldenburgh; in France, among a people who more speedily contract acquaintance, there was not a man of note with whom he did not cultivate an active acquaintance—and, fortunately, Leibnitz then lived at Paris; in Italy, he was particular cared for by Michaeli, soon after Cardinal; and was in the closest correspondence with Kircher. His enjoyments, however, were derived solely from the communications of the most eminent; his curiosity was directed to everything, and wherever he saw an ingenious artisan, he was eager to learn from him something useful. In 1682, when at Paris for the third time, he communicated to his friends his celebrated theory of the caustic curves, which marked him out as a valuable acquisition, and he was elected a member of the Royal Academy of Sciences, which was then reformed by the great minister Colbert, and the most illustrious in all nations were picked out for its ornaments. There he found himself seated with Leibnitz, Huyghens, John Bernoulli, &c.

After twelve years employed in visiting Europe, he returned home; but after a short stay, went to Flanders, and prepared to publish his work, intitled Medicina Mentis; of which the subject may almost be guessed, from the way in which he had exercised his own mind. Having the most exalted notions of the intellectual and moral moral nature of man, he thought that the continual supply of information was as necessary as the continual supply of food. And his great principle was to enlighten. This work was committed to the care of some friends, and did not appear till 1687, at Amsterdam. A second edition appeared at Leipzig in 1695.

Finding now that his moderate fortune was insufficient for the great public projects he had in view, he sought for assistance, and endeavoured to make friends by frequenting the court of the Elector at Dresden. He soon became a favourite of his Princes, George the II. and III., and was appointed to active offices of great responsibility. By the orders and encouragement of the Elector, then king of Poland, he introduced into his native country the first manufacture of glass; and his project soon threw to such a degree, that not only Saxony was supplied, but they even began to export the finer kinds of white glass for windows; in which manufacture Saxony still excels. It was in the course of experiments for improving this manufacture that Tschirnhaus made the celebrated great burning glasses which still bear his name. He made two of these lenses, and gave one to the Emperor, and the other to the Academy of Paris. He was eager to improve the art of forming and polishing optical glasses; and in the prosecution of the theory on which their performance depends, he made some beautiful discoveries in the department of pure geometry. It is well known that all the sciences are allied, and of a family, and that eminence in one is seldom attainable without the affluence of others. His present pursuits led him to the study of chemistry, which he prosecuted with the same ardour which he exhibited in every thing he undertook. But all the while, mathematics, and especially geometry, was his favourite study; and he was anxious to make the same advances in the general paths of mathematical investigation which he thought he had made in the general laws of material nature. He apprehended that only by paths were yet known, and that many things were yet inaccessible; because we had not yet found out the great roads from which those branches were derived. He was of Descartes's opinion, that the true road in mathematics must be an easy one, except in cases which were, in their own nature, complicated. Very early, therefore, he began writing on mathematical subjects, always continuing his general views of the science, and his endeavours to systematise the study; but, at the same time, bestowing a very particular attention on any branch which chanced to interest him: each of these his epistolical studies in mathematics deserves the name of a department of the science. This is the case with his theory of caustic curves, with his method of tangents, and his attempt to free Leibnitz's calculus from all consideration of infinitesimal quantities. Mr. Tschirnhaus seldom gave himself any trouble with a particular problem. In all his mathematical performances, there is an evident connection with something which he considered as the great whole of the science; and the manner of treating the different questions is plainly accommodated to a system in his thoughts. This he intended as the third part of the Medicina Mentis; and, having nearly completed the second, he had proposed the use as the occupation of the ensuing winter (1708-9). But his death, which may be called premature, has deprived the world of these, and other beneficent and useful labours.

Mr. Von Tschirnhaus was of the most mild and gentle disposition, as was well known to all who enjoyed his acquaintance. This disposition was so eminent in him, that scarcely any person ever saw him angry, or even much ruffled in his temper. He forgave injuries frankly and heartily, and often stood the friend (unknown) of those who had wronged him. By such conduct, he changed some enemies into the most steady and affectionate friendships. As an inquirer and an inventor, he had contentions with other claimants, and some disputes about the legitimacy of his methods; as, for example, with Nicholas Fatio Duiller, who attacked Tschirnhaus's method of tangents; and Prefect and Rolle, who found fault with his expression of equations of the third degree. But these were all friendly debates, and never carried him beyond the limits of gentlemanly behaviour. He began to dispute with Ozanam about a quadratrix; but on being merely told that he was mistaken, by P. Souciet, he immediately acknowledged his error, and corrected it.

Many original and important mathematical performances of Mr. Von Tschirnhaus are to be seen in the Leipzig Acts, in the Memoirs of the Academy of Sciences at Paris, and other literary journals. His happy generalisation of Dr. Barrow's theorem for the focus of a slender pencil of rays after reflection or refraction, and the theory of caustic curves, in which this terminates, both constitutes one of the most elegant branches of optical science, and affords a rich harvest of very curious and unexpected geometrical truths. The manner in which he notices the rough way in which his first and sole mistake in this theory was pointed out, is perhaps incomparable as an example of gentlemanlike reprehension, and is a lesson for literati of all descriptions, highly valuable on account of the soft way in which it falls, while it is convincing as a mathematical theorem.

Tschirnhaus was the discoverer of the substance of which the celebrated Saxon porcelain is made, and of the manner of working it up; by which he established a manufacture highly profitable to his country, and has given us the finest pottery in the world. He never wearied in spreading useful knowledge; and the hopes of our artisans of almost all kinds were supplied with books of instructions and patterns, many of them written by Mr. Von Tschirnhaus, or under his inspection. Useful books of all kinds were translated out of foreign languages at his expense. Men of genius in the arts were enabled, through the encouragement of himself and his friends, and often by his pecuniary affluence, to bring their talents before the public eye. In short, he seemed at all times to prefer the public good to his own; and never felt so much pleasure as when he could promote science or the useful arts. He was as it were stimulated to this by an innate propensity. And as he was more desirous of being than of appearing the accomplished man, he was in no concern what notice others took of his services to the public. He even represents the desire of fame as hostile to the improvement either of science or morality, in his Medicina Mentis; a work which is acknowledged by all who knew him to be a picture of his own amiable mind. He lightly esteemed riches; and knew not what use they were of, except for providing the necessaries of life, and the means of acquiring knowledge. In perfect conformity to this maxim, he modestly, and with elegant respect, refused the ample presents made him by his affectionate sovereign; and when he was added to his cabinet council, he received the diploma, but begged and obtained to be free from the title. And when he presented his great burning glads to the Emperor, and got from him the dignity and insignia of Baron of the Empire, he pleaded for leave to decline it, requesting to keep the chain and portrait, which he always wore under his vest. He expended a very great portion of the ample revenue left him by his father in the service of his country, by promoting the useful arts and sciences.

Mr Von Tschirnhaus venerated truth above all things; saying, that those who thought anything comparable with it were not the sons of God, but step-children, and that the love of truth is the ruling affection in every man of a worthy heart. In a letter to an intimate friend, he said that, by the age of five-and-twenty, he had completely subdued the love of glory, of riches, and of worldly pleasures; and that at no time he had found it difficult to repel vanity, because he was every day conscious of having acted worse than he was certain that he might and should have done. He felt himself humbled in the sight of the All perfect Judge.

Nor was all this the vain boast of a man averse to business, and possessed of an ample fortune, which permitted him, without inconvenience, to please his fancy in study, and in helping others with what to himself was superfluous. Such a character, though rare, may exist, without being the object of much respect. No: Mr Tschirnhaus was really a philosopher of the true Stoic feet, in respect of fortitude of mind, while a good Christian in modesty and diffidence. In the last five years of his life he bore up under troubles, and embarrassments, and misfortunes in his family, which would have tried the mind of Cato himself. But in the midst of these storms he was unshaken, and preserved his serenity of mind. He was even sensible of this being a rare gift of Providence, and used frequently to express his thankfulness for a treasure so precious. He felt deeply his relation to the Author of Nature, and rejoiced in thinking himself subject to the providence of God. He said that he was fully persuaded that he would meet with perfect justice, and would therefore strive to perform his own part to the utmost of his power, that his future condition might be the more happy, and that he might in the mean time enjoy more satisfaction on reflecting on his own conduct. His lot, he said, was peculiarly fortunate; having such thirst for novelty, he would have been unhappy without an affluent fortune; and his own enjoyments encouraged neither vice nor idleness in himself or in the ministers to his pleasures.

This amiable person was of a constitution not pugnacious, but not robust, and he had hurt it too constant fluidity. He feared no disease; thinking that he had a cure or an alleviation for all but one, namely, the stone and gravel. He had a dread of this, and laboured to find a preventative or a remedy. He thought that he had also done a great deal here; and describes in his Medicina Corporis a preparation of whey, which he said he used with great advantage to his health. But his precautions were in vain: He was attacked with the gravel, which, after three months suffering, brought on a suppression of urine. The physicians saw that his end approached; and finding him disregard their prescriptions, they quitted him. He treated himself (it is said judiciously) for some time, and with some appearance of successe; but at last he saw death not far off. He dictated a letter to his Sovereign, thanking him for all his favours and kindness, and recommended his children to his protection. He never fretted nor complained; but frequently, with glimmering eyes, expressed his warmest thanks to Providence for the wonderful track of good fortune and of happiness that he had enjoyed; and said that he also felt some satisfaction in the consciousness that none of this was owing to his own prudent conduct. He possessed his entire faculties to the last moment; and when he felt his spirit just about to depart, his last words were, "To triumph—Victoria!" No longer able to speak, he made signs for what he wanted; and a little after, shutting his eyes, as if to sleep, he gently, and without a groan, yielded up his spirit, about four o'clock in the morning of the 11th of October 1708, aged 56.

His funeral was performed in a manner becoming his rank, and the body conveyed to the family vault. The Elector (King of Poland) defrayed the expense; for he would not allow his family to have anything to do with the funeral of a man of so public a character, and so universally beloved.

The account of such a life as that of Baron Von Tschirnhaus would, at all times, make a pleasant and useful impression. In these our times, in the end of the 18th century, after society has availed itself of all the acquisitions in science and art, furnished by that ardent age of the world which this gentleman contributed to adorn; in an age when we boast of illumination unparalleled in history, and of improvements almost amounting to perfection; and in particular, of an emancipation from the prejudices which had obscured our view of the chief good, and stifled public spirit—now, when we are so full of knowledge that it is running over on all hands, in volumes of instruction, how to make the world one happy family; in these bright days of philanthropy, can the public records of Europe exhibit a superior character to that of Mr Von Tschirnhaus, either in respect of wisdom or of disposition? Was he not a philanthropist, a sincere lover of mankind? Was he not wise, in employing his great acquired knowledge as the means of direct and active beneficence, by limiting his exertions to the extent of those circles where his own efforts would be effective? He did not write books, teaching others how to do good; he taught it by example; being determined that his own wishes to see men happier should not fail by the want of such wishes in others, even after he should instruct them. He never allowed his insatiable curiosity for fresh discoveries to interfere with the immediate turning to the good of his own country the knowledge he had already acquired. He probably never thought of improving the situation of the Chinese or the Mexicans, finding that it required all his ample fortune, and all the interest and influence he could acquire, to do the good he wished in Saxony. We doubt not but that he was equally attentive to the... still narrower circle of duties formed by his own family. We feel that he was a dearly beloved brother; which could hardly be without his also being a loving brother and a dutiful son. The nature of the difficulties which he experienced in his family, and the manner in which he behaved under them, show him to have been an eminent Christian moralist. With a modesty that is unmatched by any one of the thousands who have poured out instructions upon us during the last ten years, and a gracefulness which characterizes the gentleman, his Medicina Mentis is offered to public notice, merely as an experimental proof that a certain way of thinking and acting is productive of internal quiet of mind; of great mental enjoyment, both moral and intellectual; and of peace, and the good will of those around us; and that it did, in fact, produce a dutiful and comfortable resignation to the unavoidable trials of human life. He pretends not to be greatly superior in wisdom to his neighbours, but merely tells how things succeeded with himself. He did not scruple, however, to publish to the world discoveries in science, in which he had got the start of others during that bury period of scientific occupation; and these discoveries in mathematics were highly prized by the first men of the age; nor will the name of Tschirnhaus, or his cautious curves, ever be forgotten.

We felt ourselves obliged to the friend who took notice of the omission of this gentleman's name, so eminent in the mathematical world, in the course of our alphabet; but when we looked into the Memoirs of the Academy of Paris for 1709 for some account of him, what we there saw appeared such a continual panegyric, that we could not take it as a fair picture of any real character. Looking about for more impartial information, we found in the Ada Eruditorum, Leipzig, 1709, the account of which the foregoing is an abstract, except a particular or two which we have copied from an account in the Literary Journal of Breslau, by Count Herberstein, whom we can scarcely suspect of undue partiality, because he had some disputes with Mr Von Tschirnhaus on mathematical subjects. May we not say, "the memory of this man is sweet!"