M O L 
the bombardment of Genoa by Louis XIV. in 1684, hav¬ 
ing caufed all the prifons to be fet open, lie efcaped to 
Placentia; and his atrocious crime met with no further 
punifhment than that of the nick-name of Pietro de Ma- 
licribiis, ftamped upon him by the facetious Italians. He 
furvived to the year 1701. Kis belt piflures Are reckoned 
to be thofe which he painted in prifon, when, indeed, he 
may be faid to have been working for his life. Pillting- 
toyi's DiS. 
MOL'YNEUX (William), an excellent mathematician 
and aftronomer, was the fon of a gentleman of a good fa¬ 
mily and fortune, and born in Dublin in the year 1656. 
As his conllitution was naturally very tender, he was in- 
flrucfted in grammar-learning by a private tutor, in his fa¬ 
ther’s houfe, till he was nearly fifteen years of age, when 
he was entered of Trinity-college in his native city. Here 
he diftinguifhed himfelf by the vigour of his abilities and 
by his exemplary manners ; and, having made a remarka¬ 
ble progrefs in academical learning, particularly in the 
new philofophy, as it was then called, was admitted to 
the degree of B. A. From this univerfity, after continu¬ 
ing in it four years, he was fent to London, and entered 
a lludent of the Middle Temple in 1675 ; where he fpent 
three years, and obtained a fufficient acquaintance with 
the law fora gentleman not intending to follow it as his 
profefiion. The bent of his genius, however, and his in¬ 
clination, leading him molt powerfully to mathematical 
and philofophical ftudies, he devoted the greateft part of 
his time to thole purfuits, to which much attention had 
then been excited in this country, by the eftablifhment 
and progrefs of the Royal Society. With thele accom- 
plilhments Mr.Molyneux returned to his native country 
in 1678, where he foon afterwards married a daughter of 
fir William Domville, the king’s attorney general. As 
he was now poflefl’ed of an eafy fortune, he continued to 
indulge himfelf in profecuting fuch branches of natural 
and experimental philofophy, as were moll agreeable to 
his tafte; and, being particularly attached to the ftudy of 
aftronomy, in 1681 he began to make aftronomical obfer- 
vations, and commenced a literary correfpondence with 
Mr. Flamfteed, the king’s aftronomer, which was main¬ 
tained for feveral years. 
Soon after this, prompted by zeal for the honour and 
intereft of Ireland, he proje&ed the defign of a Philofo¬ 
phical Society at Dublin, in imitation of the Royal So¬ 
ciety at London ; and by the countenance and encou¬ 
ragement of the celebrated fir Willian Petty, who accepted 
of the office of prefident, a weekly meeting on that plan 
began to take place in 1683, and Mr. Molyneux was ap¬ 
pointed the firft fecretary. By means of this fociety, our 
author’s icientific reputation became more wfidely ex¬ 
tended, and procured him the efteem of perfons of the 
higheft rank ; and, among others, of the duke of Ormond, 
then lord-lieutenant of Ireland, to whofe influence he was 
chiefly indebted for his appointment, in the fame year, 
jointly with fir William Robinfon, to the offices of fur- 
veyor-general of the king’s buildings and works, and 
chief engineer. In 1683, he was defied fellow of the 
Royal Society at London ; and in the fame year, for the 
purpofe of improving himfelf in the art of engineering, 
procured an appointment from the Irifh government to 
view the moll confiderable fortrelTes in Flanders. Ac¬ 
cordingly, he travelled through that country and Hol¬ 
land, and alfo through fome parts of Germany and France, 
embracing the opportunity which his letters of recom¬ 
mendation furnilhed him with, of beingintroduced to Cal- 
fini, and the other moll eminent aftronomers in the places 
through which he palled. On his return, he publifhed at 
Dublin, in 1686, his “ Sciotkericum Telefcopicum, or a new 
Contrivance of adapting a Telelcope to an horizontal 
Dial, for obferving the Moment of Time by Day or Night, 
See." a new edition of which was printed at London in 
1700, with fome improvements, in quarto. In the year 
1687, when Newton’s Principia firft appeared, he exprefled 
the fame qllonifhment, with men of fcience in general, at 
M O L 685 
fuch an effort of human genius, at the fame time that he 
modeftly intimated his doubts whether he fhould be able 
fully to become mailer of it. In anfwer to a letter of Mr. 
Flamfteed, defiring our author’s opinio nof it, an inftance 
is given of its applicability to the confirmation of im¬ 
portant religious truth, which is honourable to the judg¬ 
ment and piety of Mr. Molyneux. “One obfervation in 
the book,’’ fays he, “though not firft llarted there, is 
truly to be wondered at; and that is, the Jej'quialtera ratio 
between the periods and diftances of the planets, and that 
not only among the primary erratics, but even among 
the lefier fets of dancers. It is, in my opinion, an amazing 
thought to confider, how univerfally this great law runs 
through the whole frame of nature, and agrees to bodies 
at fuch vaft diftances, and that feem to have no tie or re- 
fpedl to each other. It is to me, beyond exception, the 
ftrongeft argument that can be drawn from the frame of 
the univerfe, for the proof of a God, to fee one law fo 
fixed and inviolable among thofe vaft and diftant Chori, 
who certainly could not therefore be put into this pof- 
ture and motion by chance, but by an omnipotent intel¬ 
ligent Being.” In 1688, owing to the confufion of the 
times, the Philofophical Society of Dublin was broken up 
and difperfed ; after our author had diftinguilhed himfelf, 
from the firft meeting, by the communication of feveral 
papers upon curious fubjedls, fome of which were fent to 
the Royal Society at London, and afterwards printed in 
the Philofophical Tranfa&ions. During the following 
year, in common with numbers of other Proteftants, he 
withdrew from the difturbances in Ireland occafioned by 
the popilh adminiftration under lord Tyrconnel: and, af¬ 
ter a fnort flay in London, fettled with his family at Chef- 
ter. Here he employed himfelf in arranging and correct¬ 
ing the materials which he had fome time before prepared 
for his Dioptrics, in which he received much afiiftance 
from Mr. Flamfteed ; and in 1690 he went to London, to 
commit it to the prefs, where the iheets were revifed by 
Halley, who, at our author’s requeft, gave leave for print¬ 
ing in the Appendix his celebrated theorem for finding 
the foci of optic glades. It was publifhed in 1692, under 
the title of “ Dioptrica Nova : a Treatife of Dioptrics, in 
two Parts: wherein the various Effects and Appearances 
of Spherical Glaffes, both convex and concave, lingle and 
combined, in Telefcopes and Microfcopes, together with 
their Ufefuinefs in many Concerns of human Life, are 
explained 4-to. He gave it the title of Nova, both be- 
caufe it was almoft entirely new, very little being taken 
from other writers, and becaufe it was the firft book that 
had appeared in Englifh upon the l’ubjeft. It contains 
feveral of the moft generally ufeful propoiitions for prac¬ 
tice, demonftrated in a clear and eafy'manner, on which 
account it was for many years much ufed by artificers; 
and the fecond part is very entertaining, efpecially in 
the hillory which it gives of the feveral optical inftru- 
ments, and of the difeoveries made by them. In the pre¬ 
face, addrefied to the Royal Society, when mentioning 
the improvements which had been made in philofophy, 
by building it upon experiment, he notices the advances 
that had been lately made in logic by the incomparable 
John Locke, who, in his Eflay on the Human Underftand- 
ing, he obferves, had rectified more received miftakes, and 
delivered more profound truths eftablifhed upon experi¬ 
ence and obfervation, for the direction of man’s mind in 
the profecution of knowledge, than are to be met with in 
all the volumes of the ancients. This compliment proved 
introduflory to an acquaintance between our phifofo- 
phers, that loon grew into an intimate friendfhip, and a 
mutual correfpondence was carried on by them as long as 
Mr. Molyneux lived, to whom many improvements in 
the fecond edition of Mr. Locke’s work are to be attri¬ 
buted. 1 
As foon as tranquillity was reftored in Ireland, Mr. 
Molyneux returned to that country ; and was chofen one- 
of the reprefentatives for the city of Dublin, in the new 
parliament convened in 5692. In the next parliament, 
in 
