otus Archimedes_ appeared at
Rome in 1603, _Nonnullae propositiones de parabola_ at Rome in 1603. and
_Apollonius redivivus_ at Venice in 1607. He was a nobleman and was
ambassador from Venice to Rome.

[124] Simon Stevin (born at Bruges, 1548; died at the Hague, 1620). He was
an engineer and a soldier, and his _La Disme_ (1585) was the first separate
treatise on the decimal fraction. The contribution referred to above is
probably that on the center of gravity of three bodies (1586).

[125] Habakuk Guldin (1577-1643), who took the name Paul on his conversion
to Catholicism. He became a Jesuit, and was professor of mathematics at
Vienna and later at Gratz. In his _Centrobaryca seu de centro gravitatis
trium specierum quantitatis continuae_ (1635), of the edition of 1641,
appears the Pappus rule for the volume of a solid formed by the revolution
of a plane figure about an axis, often spoken of as Guldin's Theorem.

[126] Edward Wright was born at Graveston, Norfolkshire, in 1560, and died
at London in 1615. He was a fellow of Caius College, Cambridge, and in his
work entitled _The correction of certain errors in Navigation_ (1599) he
gives the principle of Mercator's projection. He translated the _Portuum
investigandorum ratio_ of Stevin in 1599.

[127] De Morgan never wrote a more suggestive sentence. Its message is not
for his generation alone.

[128] The eminent French physicist, Jean Baptiste Biot (1779-1862),
professor in the College de France. His work _Sur les observatoires
meteorologiques_ appeared in 1855.

[129] George Biddell Airy (1801-1892), professor of astronomy and physics
at Cambridge, and afterwards director of the Observatory at Greenwich.

[130] De Morgan would have rejoiced in the role played by Intuition in the
mathematics of to-day, notably among the followers of Professor Klein.

[131] Colburn was the best known of the calculating boys produced in
America. He was born at Cabot, Vermont, in 1804, and died at Norwich,
Vermont, in 1840. Having shown remarkable skill in numbers as early as
1810, he was taken to London in 1812, whence he toured through Great
Britain and to Paris. The Earl of Bristol placed him in Westminster School
(1816-1819). On his return to America he became a preacher, and later a
teacher of languages.

[132] The history of calculating boys is interesting. Mathieu le Coc (about
1664), a boy of Lorraine, could extract cube roots at sight at the age of
eight. Tom Fuller, a V