f Men
Eminent in Science gives the names of some 500 Jesuits, though the
Order was not in a position to do any work in science until 1550, it
will be readily appreciated that the Popes acted wisely to encourage
an institute so prolific in _eminent_ scientists in its scientific
work at the Roman College, rather than maintain a separate scientific
department at the Vatican. The second institution would only have been
unnecessary duplication of staffs and the connection between teaching
and research at the Roman College was better for both functions.

Father Christopher Clavius, to whom more than to any other is due the
Gregorian reform of the calendar, a magnificent practical application
of astronomy and mathematics, is an excellent example {476} of the men
who were near the Popes as counsellors and scientific advisers just
before Galileo's time. Indeed Galileo and he were on the most friendly
terms until his death in 1612. The circle of his friends included such
men as Kepler, Tycho-Brahe and other great scientists of his time and
he was called "the Euclid of the sixteenth century." His works were
published at Mainz, in five huge folio volumes in a collective
edition. The third of these is a commentary upon the _Sphaera_ of John
Holywood (Joannes de Sacro Bosco, the great medieval mathematician)
and a dissertation upon the Astrolabe. The fourth volume contains a
very full discussion of Gnomonics, that is, the art of constructing
instruments of all kinds for determining the time by means of the sun.
The fifth volume contains his papers with regard to the reform of the
calendar. Most of these books were issued in many editions before and
after his death, and their publication over and over again shows very
clearly how much the men of the sixteenth and seventeenth centuries
were interested in scientific subjects and how often and quite
properly they looked to great clerical teachers as their leaders in
science.

Just about the time that the Galileo matter was disturbing scientific
and ecclesiastical circles at Rome, Father Scheiner, the Jesuit
mathematician and astronomer became Professor of Mathematics in the
Roman College. He is the inventor of the pantograph or copying
instrument for drawings, and, being of an ingenious inventive
disposition, constructed a number of instruments for astronomical
investigation. He studied the sun carefully through colored glasses in
a helioscope and then conceived the idea of projecting