REVIEW OF LE COMPTE RENDU PAR L'INSTITUT DE FRANCE. * AFTER the intercourse of England with the nations of the Continent has been so long and so unhappi. ly interrupted, it cannot but be acceptable to our readers, to receive, from the most enlightened of those nations, an account of the scientific and literary improvements that have taken place in Europe during the last nineteen years. This account is of high authority, consisting 'of reports made to the Emperor of the French by Committees of the Na. tional Institute, about the beginning of the year 1808. These reports, made by command of the Emperor, are mere abstracts or skeletons of more extensive memoirs, which we may expect hereafter to be published. Even the abstracts, however, are interesting ; not only on account of the information they contain, but as belonging to a ceremonial, From the Edinburgh Review, Vol. XV. (1809.)—ED. . a which, if not quite singular, is certainly very uncommon in the courts of princes. They are accompanied with very useful notes by the editor J. L. Kesteloot, a Dutch physician of the University of Leyden. We are told, that on the 6th of February, his Majesty being in his Council, a deputation from the mathematical and physical classes of the National Institute was introduced by the Minister of the Interior, and admitted to the bar of the Council. M. Bougainville, the oldest member, and therefore the president of the class, then addressed the Emperor in a short speech ; which we shall give in his own words. “ SIRE,--Votre Majesté Impériale et Royale a ordonné que les classes de l'Institut viendraient dans son conseil lui rendre compte de l'Etat des Sciences, des Lettres et des Arts, et de leur progrès depuis 1789. “ La classe des Sciences Physiques et Mathématiques s'acquitte aujourd'hui de ce devoir ; et si je me présente à la tête des savans qui la composent, c'est à mon âge que je dois cet honneur. « Mais, SIRE, telle est la diversité des objets dont cette classe s'occupe, que même avec la précision dont un savoir profond et l'esprit d'analyse donnent la faculté, le rapport qui en contient l'exposé exige une grande etendue. “ Ce n'est donc que de l'esquisse, et pour ainsi dire, de la préface de leur ouvrage, que MM. Delambre et Cuvier vont faire la lecture. “ Je ne me permets qu'une seule observation ; c'est que l'époque de 1789 à 1808, en même temps qu'elle sera pour les événemens politiques et militaires une des plus mémorables dans les fastes des peuples, sera aussi une des plus brillantes dans les annales du monde savant. “ La part qui est due aux Français pour le perfectionnement des methodes analytiques qui conduisent aux grandes découvertes du systême du monde, et pour les découvertes même dans les trois régnes de la nature, prouvera que si l'influence d'un seul homme a fait des héros de tous nos guerriers, nos savans, honorés par la protection de votre Majesté qu'ils ont vue dans leurs rangs, sont en droit d'ajouter des rayons à la gloire nationale." After this address from M. Bougainville, which is certainly commendable for its simplicity, though the compliment in the last paragraph might have been better turned, Delambre, secretary of the class of Mathematics, proceeded to read his Report, from which we shall select such passages as appear to us the most interesting. The Report begins with the elementary branches of the mathematics, and takes notice of two treatises which have appeared in that department within the limits of the period above mentioned,—those of Legendre and Lacroix. That of Legendre, it is said, is destined to recal geometry to its ancient severity, at the same time that it suggests some new ideas concerning an analytical mode of treating several of the elementary parts of that science. To understand these two remarks, it must be observed, that the French mathematicians, having long since abandoned Euclid, had departed also, in many things, from the rigour of strict demonstration; a practice which, in the Elements, where the foundation of the science is to be laid, was surely much to be condemned. Bossut’s Elements of Geome. try, which appeared about the year 1775, is almost the only one in the French language, except the two here mentioned, where geometrical accuracy is aimed at throughout. The work of Legendre, however, has accomplished its object more completely, we think, than that just mentioned, or, indeed, than any other modern treatise of elementary geometry. It is very extensive, including the properties of the sphere, together with the cubature and complanation of the solids bounded by planes, and also of the sphere, cylinder and cone. At the same time, the propositions contained in it are purely elementary, that is, such as, by their simplicity and generality, deserve to be considered as the fundamental truths of the science of geometry. Among those analytical methods of demonstration, to which an allusion is made above, we were long since particularly struck with one, of which, as it happens, we can convey some idea without the assistance of a diagram. It is well known to those who have compared different treatises of elementary geometry, that one of the greatest difficulties which they present, is the doctrine of parallel lines. Euclid was not able to extricate himself from this difficulty, otherwise than by the introduction of a proposition as an axiom, which certainly is by no means self-evident. Later writers have uniformly experienced the same difficulty; and some of them, trying to avoid the introduction of a new axiom, have fallen into downright paralogisms. Legendre, in his Elements, has given two demonstrations of the properties of parallel lines, without assuming any new axiom. One of these, which is contained in the text, is prolix and less simple than the nature of the theorem to be proved entitles us to expect. The other demonstration, however, which is in the notes, possesses the most perfect simplicity, at the same time that it is new; proceeding on a principle that has been long recognized, but from which no consequence, till now, has ever been deduced. If we could demonstrate, independently of all consideration of parallel lines, that the three angles of a triangle are together equal to two right angles, the object in view would be accomplished, and the difficulty, in this part of the Elements, would be en |