the Transactions of the Royal Society of Edinburgh, and in scientific journals. For the inquiry described in the first work cited, he was awarded the Rumford medal of the Royal Society of London in 1804. In the course of that inquiry, he discovered the influence of the surfaces of bodies upon their powers of radiating and absorbing heat, and the law of the relation between the direction in which heat is radiated from a surface, and the intensity of the heat so radiated; in short, he reduced the properties of radiant heat for the first time to a science. He invented the differential air thermometer, the most delicate instrument for measuring minute differences of temperature which existed previous to the invention of the thermomultiplier (which measures such differences by means of the currents of electricity that they produce). He was a strong advocate for the doctrine that heat is a condition, or force, and probably a kind of motion, not a substance; a doctrine which has been held from remote antiquity by a few of the leading minds amongst natural philosophers, such as Aristotle, Galileo, Bacon, Boyle, Newton, Davy, and Young, but whose general acceptance by scientific men is of very recent date. One of Leslie's most interesting works was a dissertation on the progress of mathematical and physical science, being one of a series of dissertations on the history of science prefixed to the Encyclopædia Britannica.—W. J. M. R.
L'ESPINASSE, Julie Jeanne Eléonore de, Mademoiselle, supposed to have been the illegitimate child of people of rank, was born in 1732. In 1754 she was engaged as a companion to the blind Madame du Deffand. The connection subsisted for some years, but she was too clever for her post. The visitors to Madame du Deffand's salon sometimes preferred the witty conversation of the companion to that of the mistress; and after enduring many of those minor miseries which perhaps only women can inflict upon each other, Mademoiselle de l'Espinasse, for whom a slight pension was obtained from government, succeeded in establishing a brilliant circle of her own. D'Alembert, whose own unhappy birth gave him a peculiar cause for sympathy with her, warmly espoused her cause, and came to reside in her house. She died on May 23, 1776. She had long been suffering—"tortured with sickness, or agitated with opium." In 1809 appeared, in three volumes, "Lettres de Mademoiselle de l'Espinasse, écrites depuis l'année 1773 jusqu'à l'année 1776;" a book which supplied Lord Jeffrey with the materials for an excellent essay in the Edinburgh Review. Curious indeed the correspondence was; the lady had a violent love for two gentlemen at once, and when one of them died she was divided between her "bésoin de mourir for M. Mora, and her delight in living for M. Guibert." Her letters are characterized by an impassioned eloquence that occasionally reminds one of the fiery fervour of George Sand; and Lord Jeffrey has described them as being "full of eloquence and spirit, and burning with the flames of a heart abandoned to passion, and an imagination exalted by enthusiasm."—W. J. P.
* LESSEPS, Ferdinand de, a French speculator, born at Versailles in 1805. At an early age he was initiated in the career of diplomacy, and after serving successively at Lisbon and Tunis, he went to Egypt in 1831. Here he more than once acted as consul for some time, maintaining French interests to the best of his power. In 1835, in consequence of his active philanthropy during the prevalence of the plague, he obtained the cross of the legion of honour. In 1838 he was consul at Rotterdam; in 1839 at Malaga; and in 1842 at Barcelona. He is said to have distinguished himself by his care of his countrymen when the latter town was bombarded by Espartero. In 1847 he obtained the rank of consul-general, and in 1848 went to Madrid as minister of the republic. In 1849 he was replaced by Prince Napoleon, and joined the legation at Berne. From Berne he went to Italy, and became entangled in the Roman troubles, which led to his suspension. Subsequently to this period he renounced the career of diplomacy and politics, and devoted his attention to a scheme with which his name will be permanently allied, the Suez canal, by which he proposed to join the Mediterranean and Red Sea by a canal of sufficient dimensions to allow the passage of ships. This magnificent undertaking was so far finished, that the canal was officially opened in 1869.
LESSER, Friedrich Christian, a native of Nordhausen, where he was born in 1692, and died in 1754. After studying medicine, he took to theology, and became a minister. He wrote "A Natural History of Stones," "Insectotheologia," "Testaceotheologia," and "Heliotheologia."—B. H. C.
LESSING, Gotthold Ephraim, was born January 22, 1729, at Kamenz in Upper Lusatia, of which his grandfather was then burgomaster. Among his ancestors, all of whom for several generations were distinguished for learning, was Clemens Lessing of Chemnitz, who signed in 1580 the Formula Concordiæ. His father Johann Gottfried, author of Vindiciæ Reformationis Lutheri, &c., studied at Wittenberg and became catechist, then deacon, and ultimately minister of his native town. He married in 1725 the eldest daughter of Feller, his predecessor, who bore him ten sons and two daughters. Gotthold Ephraim as the eldest surviving child, was in his youth, according to the traditional custom of the family, dedicated to the ministry. He was sent first to the grammar-school of his native place, and subsequently, when he had reached the age of twelve, to the Fürstenschule at Meissen. Here he not only eclipsed all his compeers in the business of the school, but read and imitated in German verse Plautus, Terence, and Anacreon; translated the second, third, and fourth books of Euclid; collected data for a history of mathematics, and wrote the outlines of one of his plays, "Der junge Gelehrte." On leaving the Fürstenschule which he did in 1745, a year before the expiry of the usual period of residence, he delivered a valedictory oration "De Mathematica Barbaroram" In the autumn of 1746 he was sent by his parents to Leipsic, to be trained for the ministry. After the first two or three months of his residence at the university, however, he seems to have abandoned altogether the lectures of the theological professors, and to have spent his time in fencing, dancing, vaulting, polite conversation, and reading plays. Christlob Mylius, a clever and accomplished, but somewhat disreputable person, was his principal associate, in company with whom he attended the philosophical courses of Kaestner, Ernest, and Christ, and by whose advice he was persuaded to renew his acquaintance with mathematics with a view to the prosecution of physical inquiries. In the two periodicals which Mylius successively commenced in the years 1746-48, Lessing contributed some lyrical pieces, epigrams, and "Damon" a comedy. In the latter year his comedy, "The Young Scholar," was produced on the stage at Leipsic, with which event originated his intimacy with such celebrities as Koch the actor, and Weisse the dramatist. After Easter of this year, having returned from a visit to his parents, he resolved to follow Mylius who had gone to Berlin. It was not, however, till the beginning of 1749 that he reached the capital of Prussia; for having fallen in on the journey at Wittenberg, he had there entered the university as a student of medicine, and remained some months. During the earlier part of his residence in Berlin he learned Spanish, finished some of his plays, commenced his essay on the pantomimes of the ancients, and edited in conjunction with Mylius the Beiträge zur Historie und Aufnahme des Theaters. In 1751 he commenced to contribute a series of learned articles to the Die vossische Zeitung, and in the same year published his minor poems under the title of "Kleinigkeiten." In the following year he commenced to prepare for the press a collection of his works, in six parts, which was published at Berlin, 1753-55. From the last-mentioned place dates his acquaintance with Moses Mendelssohn and with Nicolai. In conjunction with the former he produced a work on the ethical characteristics of Pope the poet; and with both he corresponded on the subject of classical tragedy. In October, 1755, Lessing returned to Leipsic. Six months of the following year he spent in travelling in company with a wealthy merchant, and in 1757 again went to Berlin, this time to enjoy the society of his new friend Kleist. In 1759 he published his "Fables," "Essay on Fables," and "Philotas," a tragedy. The "Life of Sophocles," and the translation of Diderot's Theatre followed in 1760, at the end of which year Lessing became secretary to General Tauentzien, governor of Breslau. Here he read Spinoza and the fathers of the church, and wrote the first part of his "Laokoon," which he published in 1766. In 1767 he wrote his play, "Minna von Barnhelm," which was published four years later. After another brief residence in Berlin, Lessing accepted an invitation to Hamburg to arrange the affairs of an association recently formed in that city, for the improvement of the drama. The task was impracticable, and the unlucky poet-manager for a time took refuge in the business of bookselling and printing. But neither did this succeed, and he was on the point of starting for Rome as a literary adventurer, when he fortunately received the appointment of ducal librarian at Wolfenbüttel. In 1772 he
