One of his biographers calls him “the Galen, the Ibn Sina, the Fernel of his age.” Another remarks that he was, perhaps, the greatest physician of modern times: “A man who, when we contemplate his genius, his erudition, the singular variety of his talents, his unfeigned piety, his spotless character, and the impress which he left not only on contemporaneous practice, but on that of succeeding generations, stands forth as one of the brightest names on the page of medical history, and may be quoted as an example not only to physicians, but to mankind at large. No professor was ever attended, in public as well as at private lectures, by so great a number of students, from such distant and different parts, for so many years successively; none heard him without conceiving a veneration for his person, at the same time that they expressed their surprise at his prodigious attainments; and it may be justly affirmed, that none in so private a station ever attracted a more universal esteem.” REFERENCES.--“Biographica Philosophica,” Benj. Martin, London, 1764, pp. 478–483; “Eloge de Boerhaave,” by Maty, Leyde, 1747, and by Fontenelle, 1763, T. VI; his life, written by Dr. Wm. Burton, London, 1736; Van Swinden, “Recueil,” etc., La Haye, 1784, Vol. II. p. 354, note; “La Grande Encyclopédie,” Tome VII. p. 42; “Biographie Générale,” Tome VI. pp. 352–357; “Biographie Universelle,” Vol. IV. pp. 529–555; Ninth “Encycl. Britannica,” Vol. III. p. 854; “Histoire Philosophique de la Médecine,” Etienne Tourtelle, Paris, An. XII. (1807), Vol. II. pp. 404–446; “Bibl. Britan.” (Authors), Rob. Watt, Edinburgh, 1824, Vol. I. p. 127; “The Edinburgh Encyclopædia,” 1830, Vol. III. pp. 628–630 or the 1813 ed., Vol. III. pp. 612–614; G. A. Pritzel, “Thesaurus Literaturæ Botanicæ,” Lipsiæ, 1851, p. 26. =A.D. 1744.=--Ludolf--Leudolff--(Christian Friedrich), of Berlin, first exhibits, January 23, the ignition of inflammable substances by the electric spark. This he does in the presence of hundreds of spectators, on the occasion of the opening of the Royal Academy of Sciences by Frederick the Great of Prussia, when fire is set to sulphuric ether through a spark from the sword of one of the court cavaliers (see notes on Tyndall’s second lecture, 1876, p. 80). It was likewise at this period Ludolf the younger demonstrated that the luminous barometer is made perfectly electrical by the motion of the quicksilver, first attracting and then repelling bits of paper, etc., suspended by the side of the tube, when it was enclosed in another tube out of which the air was extracted (_Dantzig Memoirs_, Vol. III. p. 495).