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

Terrestrial and Celestial Globes.
considerable advance in the practical construction of terres-
trial globes, for it seems reasonable to conclude that they
were in possession of such objects when writing, as they did,
concerning them.
Ptolemy, we may note, expressly allowed that the size of a
globe should be that which one might desire, and that it
was not necessary it should be of large
who first
size. It was this
demonstrated the
great Alexandrian cosmographer
scientific value of drawing on the surface of a globe or map
the network of parallels and meridians, and of establishing
by means of the two geographical coordinates the true geographical
position of every known place. To the end of
making globes more serviceable he suggested the use of a
meridian circle, such as is today employed in globe con-
struction, passing through both poles, within which circle
the globe might be made to move freely on its axis. He,
however, in this connection, did not give technical direc-
tions for the construction of terrestrial globes, but he says
enough to assure us that the art of globe construction was
measurably well understood in his day, and that the Greeks
and the Romans considered them very useful instruments in
the study of the heavens and the earth. ^^
The allusions of the naturalist Pliny (23-79) ^^ ^^^
spherical shape of the earth give us no particular intimation
that he knew of the existence of terrestrial globes, but they
are interesting as indicating a belief of his time in its
spherical form, a belief, judging from the nature of the
argument, apparently drawn from Aristotle. Referring to
the shape of the earth, he observes that "everyone agrees it
has the most perfect figure. We always speak of the ball of
the earth, and we admit it to be a globe bounded by the
poles. It has not indeed the form of an absolute sphere, from
the number of lofty mountains and flat plains; but if the
termination of the lines be bound by a curve, this would
compose a perfect sphere. And this we learn from arguments
drawn from the nature of things, although not from the
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