GUG 
upon him for his impiety. He was the au- 
thor of several treatises in natural philoso- 
phy, the principal of which is entitled 
“ Experimenta Magdeburgica,” 1672, folio, 
and contains his experiments on a vacuum. 
GUETTARDA, in botany, a genus of 
the Monoecia Heptandria class and order. 
Natural order of Tricocc®. Rulnace®, 
Jussieu. Essential character: calyx cylin- 
dric ; corolla six or seven-cleft, funnel- 
shaped ; pistil one ; drupe dry. There are 
four species, natives of the East and West 
Indies. 
GUGLIELMINI (Dominic), an emi- 
nent Italian mathematician and civil engi- 
neer, was descended from an honourable 
family, and born at Bologna in the year 
1655. His favourite studies were the ma- 
thematics and medicine, in the former of 
which he had for tutor the celebrated M. 
Germ. Montanari; and in the latter, the 
illustrious Malpighi. He entered into the 
dispute between M. Montanari and M. 
Cavina, concerning the extraordinary lumi- 
nous meteor, which was observed in most 
parts of Italy in 1676, and supported the 
opinions of l'lis master. In the year 1678 
he was admit ted to the degree of doctor of 
medicine by the university of Bologna. 
Upon the appearance of the remarkable 
comet in the yews 1680 and 1681, he pub- 
lished a treatise “ De Cometarum Natura 
et Ortec,” &c. 1681, in which he pro- 
posed 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 approbation 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 La- 
tin at Bologna, in the same year, reflected 
creater credit on his knowledge and accu- 
racy 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 inten dan t- general of the rivers of the 
Bolognese. The office last mentioned en- 
gaged him to pay more particular attention 
to die study of hydrostatics and hydraulics ; 
in consequence of which, in the year 1690, 
he published the first part, and in the fol- 
lowing year the second part, of an excel- 
lent hydrostatical treatise, entitled “ Aqua- 
rum Fluentium Mensura, Novo Methodo 
Tnquisita.” Some of his observations in 
this work were attacked by M. Papin, 
who aim entered into a contest with the 
GUG 
author on the subject of Syphons. Their 
difference in opinion gave rise to two let- 
ters by Guglielmini, which were printed un- 
der the title of “ Epistol® Du® Hydrosta- 
tic®.” He was engaged in settling the dif- 
ferences which arose between the cities of 
Bologna and Ferrara respecting the manage- 
ment of the embankments and sluices in 
their contiguous districts ; and received 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 bydrometry. In the year 1695 he as- 
sisted M. Cassini in repairing the famous 
meridian line which he had constructed 
forty years before in the church of St. Pe- 
tronius, at Bologna; on which occasion our 
author published a memoir, descriptive of 
the method pursued 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 nature of rivers, entitled “ Della Na- 
tnra de Fiumi,” which raised his reputation 
to the highest pitch, for correct scientific 
knowledge, ingenuity, and judgment in hy- 
draulics. Montucla commends it in warm 
terms, and says that it ought to be care- 
fully studied by every person who would 
wish to become thoroughly master of this 
branch of science. The reputation which 
Guglielmini acquired by this performance, 
occasioned his being employed by the Dukes 
of Mantua, of Parma, and Modena, the 
Grand Duke ofTuscany, Pope Clement XI. 
the Republics of Venice and Lucca, &e. in 
the invention and construction of the neces- 
sary hydraulic works in their respective 
territories. In the year 1698 he was in- 
duced, by the Republic of Venice, to ac- 
cept of the mathematical chair in the uni- 
versity of Padua ; but the senate of Bo- 
logna decreed that he should still retain, 
notwithstanding his new employment, the 
title of professor in their university, and 
the emoluments annexed to it. In the 
year 1702, he exchanged his mathematical 
chair at Padua, for the more lucrative one of 
medicine ; after which he published differ- 
ent treatises on medical and chemical sub- 
jects, &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 corresponding member 
of the Academies of Berlin and Vienna, 
and of the Royal Society at London. The 
best edition of his treatise on the nature of 
rivers, was published at Bologna in 1756, 
