# Dechales, Claudius Francis Millet

, an excellent mathematician, mechanic, and astronomer, was born
at Chamberry, the capital of Savoy, in 1611; and descended from a noble family, which had produced several
persons creditably distinguished in the church, the law, and
the army. He was a great master in all the parts of the
mathematics, and printed several books on that subject,
which were very well received. His principal performances
are, an edition of Euclid’s Elements, where he has struck
out the unserviceable propositions, and annexed the use
to those he has preserved; a discourse of fortification;
and another of navigation. These performances, with
some others, were first collected into three volumes in
folio, under the title of “Mundus Mathematicus,” comprising a very ample course of mathematics. The first
volume includes the first six books of Euclid, with the
eleventh and twelfth; an arithmetical tract; Theodosius’s
spherics; trigonometry; practical geometry; mechanics;
statics; universal geography; a discourse upon the loadstone; civil architecture, and the carpenter’s art. The
second volume furnishes directions for stone-cutting; military architecture; hydrostatics; a discourse of fountains
and rivers hydraulic machines, or contrivances for waterworks; navigation; optics; perspective; catoptrics, and
dioptrics. The third volume has ki it a discourse of music
pyrotechnia, or the operations of fire and furnace a discourse of the use of the astrolabe gnomonics, or the art
| of dialling; astronomy; a tract upon the calendar; astrology; algebra; the method of indivisible and conic sections. The best edition of this work is that of Lyons,
printed in 1690; which is more correct than the first, is
considerably enlarged, and makes four vols. in folio. Dechales, though not abounding in discoveries of his own, is
yet allowed to have made a very good use of those of other
men, and to have drawn the several parts of the science
of mathematics together with great clearness and judgment. It is said also, that his probity was not inferior to
his learning, and that both these qualities made him generally admired and beloved at Paris; where for four years
together he read public mathematical lectures in the college of Clermont He then removed to Marseilles, where
he taught the art of navigation; and aiterwards became
professor of mathematics in the university of Turin, where
he died March 28, 1678, aged 67. ^{1}

^{1}

Moreri & —Dict. Hist. in Chales.