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the earth and to certain astronomical measurements of distance which have only
been rediscovered lately. Their corners are in line with the four points of
the compass, and in the royal burial chamber there is a mirror which looks up
at all times, through a long inclined tunnel, to the polar star. Whoever was
capable of making such calculations possessed abilities and scientific
knowledge, a gift of observation, and a mental power which even the first
great men of our modern astronomy Copernicus, Kepler, Galileo, and Isaac
Newton did
not surpass."
"You are right," acknowledged Schulze. "The ancients had tremendous minds
which, without our modern auxiliaries, without telescopes and spectral
analysis, achieved al
most as much as our most modern scientific notables with all the advantages of
the colossal work of their predecessors and the most perfect instruments.
"The Greek philosopher Bion, 500 years before Christ, taught the spherical
form of the earth and contended that there must be regions on our earth on
which there are six months of daylight and six months of night. Eratosthenes
of
Alexandria calculated the circumference of the earth with startling
penetration and astounding exactness, coming to approximately the same result
the Chaldeans had come to long before him.
"The geographer, Strabo, had forebodings about America, for he said that there
could still be two or more unknown continents on the globe. Aristarchus made
bold enough to calculate the distance and the dimensions of the moon and the
sun, considering, it is true, the distance to the sun 20 times as great as
that to the moon, instead of 400.
Nevertheless, these were measurements which must have appeared positively
enormous in those day. Posidonius furnished a truly wonderful calculation of
the earth's atmosphere and of the refraction of light, and just as astounding
is his calculation of the size of the sun. We have no idea what means he used
to arrive at such dumbfounding results."
"Permit me," Hank interrupted the Professor, "to tell you how I imagine a sage
of antiquity could have arrived at the correct conception of the distances and
sizes of the world bodies.
"Let us assume that a Greek philosopher climbed the Helicon with his pupils.
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'Look down,' he said to them, 'upon that field at the foot of the mountain,
which seemed so extensive to us when we passed it by, and now, from above
here, because of the distance, appears to be a tiny spot, a good hundred times
smaller than it really is. The distance we have
put behind us in climbing up from the field has brought us that much closer to
the moon. And yet its disk does not look one bit larger to us than it did down
below. The moon must therefore be quite immeasurably farther removed from us
than that field, so that the height of the Helicon means very little in
approaching it. But if it is at such a great distance then it must, in
reality, be infinitely larger than it appears. The sun must be still farther
off and larger, for when there is a solar eclipse the moon goes by beneath it.
Also, the earth must be spherical in form; for the higher we climb the more we
can survey, and that holds true for every mountain top, in Asia Minor and
Africa as well as here.' "
"True enough," admitted Schulze, "such considerations might have led the
ancients on to the right road. Nevertheless, we must marvel at how clear were
their ideas, which were able, as a result of such observations, to rise above
the conceptions of their day.
"Apollonius of Perga was such a mental giant and is said to have discovered
the idea of parallaxis, that is, the method of calculating the distance of the
stars. Hipparch calculated the umbra of the moon with great exactitude and
deduced from it the distance from the sun to the moon.
"Pythagoras taught the movement of the earth as the reason for the apparent
movement of the stars; Aristarchus recognized that the earth revolves around
the sun and that the fixed stars are located at an enormous distance from us.
All this, moreover, seems to have been recognized by Democri-tus four
centuries before Christ.
"Archimedes already had the first ideas about gravitation. But all these bold
advances lay fallow and forgotten for centuries until Copernicus wrote his
great work, whose prophet the luckless Giordano Bruno proclaimed himself to
be.
"Then came Tycho Brahe, the great observer to whom Kepler owed so much. Johann
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