Terrestrial and celestial globes; their history and ... - 24grammata.com

Globes in the Christian Middle Ages.
pano was acquainted with the work of Alfonso. His presentation
of the subject, in all probability, was altogether
of the Alfonsian tables. It is
independent of a knowledge
interesting to observe that in the day when astrology was
in great favor in the universities of Europe, Campano con-
tinued to be interested in genuine astronomical science.
x\lbertus Magnus, in his 'Liber de coelo et mondo,'"^ de-
votes an entire chapter to a theoretical consideration of
gravitation, asserting that the earth is spherical (Spherica
sive orbicularis necessario), and proceeds to a demonstra-
tion of the theor}% in which he practically follows the
arguments of Aristotle, that ever}' particle of the earth away
from the center is continually in movement seeking that
center, the result being the formation of a spherical body.
He advances further, as argument in proof of a spherical
earth, that the shadow it casts in an eclipse of the moon is
circular.
Sacrobosco (John of Holywood or Halifax) (fl. 1230),"
who was active in the first half of the thirteenth centur}',
much of the time as professor of mathematics in the Uni-
versity of Paris, prepared a work bearing the title, 'Tractatus
de sphaera,' being in part a summary of the 'Almagest'
of Ptolemy. In this work the theory of a spherical earth is
supported in much the same manner as was done by Cam-
pano. The 'Tractatus' proved to be one of the most important
quasi scientific geographical and astronomical textbooks
of the later middle ages, being frequently copied, and
frequently printed after the invention of that art."^
Further reference might be made to a belief in a spherical
earth, as held by Roger Bacon (1214-1294),"^ by Thomas
Aquinas (1225-1274)," by Vincent of Beauvais (1190-
1264),"*' by Dante (1265-1321),''
and still others of the
thirteenth, fourteenth, and fifteenth centuries. It should,
however, be stated that nowhere in the works of these
authors does there appear a reference to the construction
of terrestrial globes, and only incidentally the implication
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