GUGLIELMINI (Donouvic), an eminent Italian mathematician and civil engineer, was descended from an honourable fami ly, and born at Bologna in the year 1655. His favourite studies were the mathema tics and medicine, in the former of which he had for tutor the celebrated M. Germ. Montanari ; and in the latter, the illus trious Malpighi. He entered into the dispute between M. Montanari and M. Cavina, concerning the extraordinary luminous meteor which was observed in most parts of Italy in 1676, and support ed the opinions of his master. In the year 1678 he was admitted to the de gree of doctor of medicine by the uni versity of Bologna. Upon the appear ance of the remarkable comet in the years 1680 and 1681, he published a treatise " De Cometarum Natura et Or tee," &c. 1681, in which he proposed a new system on the subject, which he thought would serve to explain all the phenomena of those heavenly bodies ; but it did not meet with the approba tion of the scientific world. His next astronomical treatise, containing remarks on the solar eclipse which took place on the 12th of July, 1684, and which he published in Latin, at Bologna, in the same year, reflected greater credit on his knowledge and accuracy of observation. Soon afterwards the Senate of Bologna appointed him principal professor of mathematics in the university of that city, and in the year 1686, created him intendant-general of the rivers of the Bolognese. The office last mentioned engaged him to pay more particular at tention to the study of hydrostatics and hydraulics ; in consequence of which, in the year 1690, he published the first part, and in the following year the se cond part, of an excellent hydrostatical treatise, entitled" Aquarum Fluentium Mensura, Novo Methodo I nquisita." Some of his observations in this work were at tacked by M. Papin, who also entered into a contest with the author on the subject of Syphons. Their difference in opinion gave rise to two letters by Gugli elmini, which were printed under the ti tle of " Epistolx Dux Hydrostaticx." He was engaged in settling the differences which arose between the cities of Bo logna and Ferrara, respecting the man agement of the embankments and sluices in their contiguous districts ; and receiv ed as a reward of his services, from his native city, the appointment to a new office in the university, which was that of professor of hydrometry. In the year
1695 he assisted M. Cassini in repairing the famous meridian line, which he had constructed forty years before in the church of St. Petronius, at Bologna ; on which occasion our author published a memoir, descriptive of the method pur sued in laying it down, and establishing its claims to correctness and accuracy. In the year 1697 he published his grand physico-mathematical treatise on the na ture of rivers, entitled " Della Natura de Fiumi," which raised his reputation to the highest pitch, for correct scienti fic knowledge, ingenuity, and judgment in hydraulics. Montucla commends it in warm terms, and says that it ought to be carefully studied by every person who would wish to become thoroughly master of this branch of science. The reputation which Guglielmini acquired by this per formance occasioned his being employed by the Dukes of Mantua, of Parma, and Modena, the Grand Duke of Tuscany. Pope Clement XL the Republics of Ve nice and Lucca, &c. in the invention and construction of the necessary hydraulic works in their respective territories. In the year 1698 he was induced, by the Republic of Venice, to accept of the ma thematical chair in the university of Pa dua; but the senate of Bologna decreed that he should still retain, notwithstanding his new employment, the title of profes sor in their university, and the emolu ments annexed to it. In the year 1702, he exchanged his mathematical chair at Padua for the more lucrative one of me dicine ; after which he published diffe rent treatises on medical and chemical subjects, &c. He died at Padua in 1710, in the fifty-fifth year of his age. He had been admitted a member of the Academy of Sciences at Paris in the year 1696, and was also associate or corres ponding member of th e Academies of Ber lin and Vienna, and of the Royal Society at London. The best edition of his trea tise on the nature of rivers was published at Bologna in 1756, with the notes of Man. frcdi ; and the whole of his works were printed in a collective form at Geneva, in 1719, in two volumes quarto.