e middle of the
fifteenth century are very well known. Toscanelli's services to
astronomy are only {473} less famous than those to cosmography. A
series of his careful and painstaking observations and calculations of
the orbits of the comets of 1433, 1449-50, of Halley's comet of 1456
and of the comets of 1457 and 1472 are preserved in manuscript. They
demonstrate his profound and successful interest in astronomical
subject and it is easy to see that they must have cost him, as indeed
he tells in his letters, many a night's watching of the stars. The
relations between the ecclesiastical authorities and Toscanelli are
very well illustrated by that well-known monument to his astronomical
skill which still interests visitors so much in the Cathedral of Santa
Maria del Fiore at Florence. This is the gnomon arranged in the dome
of the Cathedral by the shadow of which it is said that he could
determine midday to within half a second. The use of the Cathedral for
this purpose is interesting testimony to the cordial relations of
science and religion at this time. It may be said in passing that
Toscanelli's gnomon was later improved by Cardinal Ximenes of Spain,
showing that these cordial ecclesiastical relations with science were
not confined to Italy.

While Toscanelli was making his observations Antoninus of Florence was
for some thirteen years the Archbishop of the city and was one of the
learned members of the Dominican Order at this time, who had made his
novitiate among the Dominicans with Fra Angelico and Fra Bartholomeo
the great Renaissance painters. Antoninus was greatly influenced
evidently by his associations with Toscanelli and formed one of a
group of men containing the Florentine physician astronomer, Cardinal
Cusanus and Regiomontanus, himself afterwards a bishop, who were on
terms of intimate relationship at least in scholarly matters at this
period. Archbishop Antoninus, who is the author of a _Summa Theologica
Moralis_ of which no less than fifteen editions were printed after his
death, wrote also a series of histories in which he shows this
influence by insisting that comets are celestial bodies like the
others in the heavens and had no effect on the physical or moral
conditions of the world and, quite contrary to popular beliefs, were
not responsible for war or pestilence nor prophetic of evil to
mankind. There had been a number of brilliant comets in the heavens
about this time and there was consequently