HORUS VOL II. Issue 3
A Hypothetical Ancient Telescope
Francis G. Graham
The telescope is traditionally thought to have been invented around 1608 and first used astronomically by Galileo in 1610. However, there are numerous instances of
Renaissance "discoveries" actually being rediscoveries of ancient knowledge. Electroplating, mechanical clocks, steam engines, concentrating mirrors, and the
circumnavigation of Africa are certain and sure examples. Since less than ten percent of the writings of the ancient world survive, it is likely there are many more examples of
Archaeological evidence from Pompeii shows that the ancient Romans used water-filled glass globes to magnify words on manuscripts. Later, and independently, the tailors
and seamstresses of the Pennsylvania Harmonite Society discovered the uses of glass globes as lenses when these glass globes were filled with water, circa 1845. It's likely
that the magnification abilities of glass globes filled with water have been discovered many times in the past and applied to practical problems of observation.
[*!* Image: Magnification by glass globe filled with water]
[*!* Image: Glass globe lens in Old Economy, a Harmonite community. It was used for sewing]
I therefore decided to investigate the conjecture that the ancients used water-filled glass globes to construct a telescope. It is important to realize that this experiment does not
prove glass globes were used to make telescopes, but only that a simple extension of technology the ancients possessed could have resulted in such a device. But no remains
of an ancient glass globe telescope have ever been found.
It is a simple matter to take a large glass globe filled with water, and perhaps, on an afternoon of lazy curiosity, place it in front of a smaller water-filled glass globe. At that
point, looking through the two, one would behold an inverted magnified image of a distant scene. Or perhaps, such a scribe using a waterfilled globe to magnify some small
writing may have thought that two globes were better than one, and so, operating in the same fashion, an inverted distant scene would have been brought much closer. One
could even dispense with a pair of glass globes; a single water-filled glass globe looking into the rounded concave polished interior of a serving spoon would have revealed a
magnified, inverted distant scene brought much closer. To summarize: the chances for discovering a telescope in ancient society once magnification was discovered are quite
large; it would be almost surprising, actually, if someone did not stumble over it.
In the spirit of Thor Heyerdahl's Kon-tiki and Ra experiments, one can create hypothetical situations from ancient technology even though they are not in the historical
record. I therefore took two spherical water-filled glass globes, of 1000 mI and 25 mI capacity, and brought them together to form an optical system in which the 1000 ml
flask was the objective and the 25 mI flask served as the eyepiece. The system focused parallel rays of light when the globes were held nine centimeters apart.
[*!* Image: The hypothetical ancient telescope as assembled and used. LABELS: spherical flasks filled with water for magnification]
Initial observations were made April 11, 1978, and the Moon appeared wondrous in the telescope. Words simply fail in describing the beauty of a nearly full Moon magnified
by water! The craters Tycho, Copernicus, Plato and the Alps were easily visible. I repeated these observations November 4, 1984. It is apparent that any ancient astronomer
viewing the moon under such circumstances would not fail to recognize that the Moon has a landscape.
I next aimed the hypothetical ancient telescope at Jupiter. After the most careful adjustment, the optical centers were lined up and the astigmatism reduced. The disk of that
planet was full of rainbow chromatic images caused by the crude nature of the optical system. Nevertheless, out of the halo, were the two tiny dots of two Galilean moons of
Jupiter next to the planet. The other two apparently did not at that time have an angular separation large enough to escape the imperfect image.
Saturn was next but, in spite of the most careful painstaking adjustment, the rings of Saturn were beyond the capabilities of this combination of water-filled glass globes. Yet,
a more complex optical system of water-filled globes might have resolved it.
Additionally, stars were visible in this hypothetical ancient telescope which were not visible to the eye.
On August 18, 1978 I aimed the telescope at Venus. One could see the 50% illuminated disk of that world. A crescent Venus would have been still more visible because of its
larger angular size.
Basically, these experiments show that the ancients could have done astronomy with such devices as their technology had already created, but can not prove that they did. We
need additional evidence to suggest that they did use such telescopes.
We turn, therefore, to the ancient record in hopes of finding clues to suggest that at least some observations could not have been made with the unaided eye.
Ancient observations of the Moon
Most of the work on the subject of the Moon in the ancient world consisted of integrating it into a cosmological perspective. To the ancient scientists of Alexandria's Library,
the Earth was fixed in the center of the universe and the only question was the precise nature of the Moon's orbit. Both Aristarchus and Ptolemy had determined its size and
distance within 10% error. The Earth was fixed, and all the motions of the Moon and the planets around it were fourier-analyzed by Claudius Ptolemy that is, resolved into a
combination of circular motions. This allowed the ancient astronomers to determine that the Moon was slower at its apogee and faster at its perigee, in accordance with the
later discovered laws of Johannes Kepler in the 17th Century. It also allowed the ancient astronomers to predict solar and lunar eclipses, and allowed solar and lunar
calendars to be set down with great accuracy.
[*!* Image: The Alpine Valley on the Moon [NASA]]
Having accomplished this, there was not a great deal to say about the physical nature of the Moon or planets by Ptolemy or the other cosmologists. Not one lunar drawing
was found before the 16th century. The later copyists, who immortalized Ptolemy's system, were more concerned with a world-view and its uses for navigation and prediction
of phenomena than with actual physical drawings of individual objects that may or may not have been telescopic. It seems unthinkable that no ancient artists ever sketched
the features visible in the face of the Moon with the eye alone. Yet, none have survived partly due to the higher priority given to translating, reproducing and distributing the
In spite of this, a few very precise verbal descriptions of the Moon's surface have come down to us; unfortunately these are second-handed, from other commentators.
Plutarch (46-120) was a biographer famous for his Parallel Lives. For this reason, even his minor works were copied and preserved. One of his short essays in a collection of
short essays on morals is sadly out of place. It's called "On the face in the Disk of the Moon", and, alas, part of it too is lost.
At that time there were competing theories about the physical nature of the lunar surface. Aristarchus held that the Moon was a solid body of its own with a unique landscape:
mountains, "hollows", etc. The other theory, created by Clearchus, was that the Moon was a crystalline sphere reflecting the landscape of the Earth.
Clearchus noticed the similarity between the lunar sea pattern and the map of the Mediterranean Sea area which, then, was the presumed center for the world's known surface.
He also thought that the crater we can Tycho, whose rays are visible only near full Moon, and which otherwise is not at all conspicuous, was the reflected image of the Sun.
The Alps and Apennine mountain ranges on the Moon, named on the Moon for their similar positions in the Mediterranean Sea analogy, are a holdover from Clearchus' ideas.
Plutarch's essay is a dialogue between proponents of the two theories. Both theories, note, accepted the landscape visible on the Moon; it was just a question of whether the
landscape was indigenous to the Moon or a reflection of the Earth.
Plutarch goes on to describe the prominent lunar topography, and it would be a tribute to extremely keen vision if it were done without a telescope. But he goes further: he
described how the heights of lunar mountains could be measured by measuring the length of their still longer shadows at sunrise or sunset. He mentions as a specific analogy
6350 ft. Mt. Athos in Greece, which near sunset casts a shadow 50 miles across the Aegean sea to the island of Lemnos, where it darkened a brass cow that was built by the
people there. It is difficult to determine whether Plutarch was describing an observation which might be made or which had been made, and the remainder of the essay which
might have clarified this is lost; but it is certain that, if the shadows of lunar mountains actually were observed, they are several standard deviations from the visual acuity of
the human eye alone. In short, such an observation is impossible without a telescope.
[*!* Image: The Full Moon as seen from space [NASA]]
There are many ancient observations of Venus as a crescent and symbolic depictions with crescents of the goddesses representing Venus. Personified as Ishtar or Astarte,
crescents appear everywhere temples or votive structures are found. Astarte bore a crescented staff. Even in the Judeo-Christian tradition, Satan is also called Lucifer, the
"bearer of light. In ancient Hebrew tradition, according to the Encyclopedia Britannica, Lucifer is also associated with Venus the planet. Lucifer traditionally is represented
with two horns. Are these the cusps of the crescent planet Venus?
The Venus crescent can get as large as ½ arc-minute, which is just beyond the resolution of the normal eye and possibly within the range of people with exceptional visual
acuity. But at that time, it is very near inferior conjunction and the crescent is very thin. At the time when Venus looks like the crescents of the goddess, it is only one-third of
this apparent size. 1 wonder, then, if some kind of crude telescope were used to see Venus in the crescent phase.
There are other astronomical observations of the ancient world which seem to require telescopes, and undoubtedly more will surface. In Ptolemy's Quadripartite, an
astrological text, we find references to the Praesepe cluster which is difficult to see as individual stars, without a telescope. Objection might be raised to the telescope theory,
since the full-phase of Venus, or anything past half-phase, was disproof of Ptolemy's planetary system. However, then Venus is difficult to see with the kind of crude glass
globe telescopes we are considering, because of its smaller angular size.
Nevertheless we've suggested a case for the ancients having had occasional access to crude telescopes. We cannot discount extraordinary natural vision, or even lucky
guessing, as the cause of these observations, but I merely offer the telescope hypothesis as one to be considered. Its acceptance depends in part on the prejudices and
dispositions we have toward the intelligence of our forefathers a mere hundred generations ago. Although the amount of truly scientific knowledge has increased a
millionfold, I believe the basic inventiveness of the human mind is no different than one sees today. The ultimate demonstration, of course, will be when an archaeologist
actually finds an ancient telescope.
[*!* Image: Ishtar with a crescent above her head as shown on an ancient Babylonian chalice]