STREPSIADES Have you ever seen a beautiful, transparent stone at the druggists', with which you may kindle fire?
SOCRATES You mean a crystal lens.
STREPSIADES That's right. Well, now if I placed myself with this stone in the sun and a long way off from the clerk, while he was writing out the conviction, I could make all the wax, upon which the words were written, melt.
Aristophanes 420 BC, THE CLOUDS

It is supposed that ancient Greeks did not use optical lenses and that optical instruments were discovered 1000 years later. But is this true? For example there are images in Peru with a person looking with something that looks like a telescope and the object behind him in the sky seems to be a comet. A similar image exists (without the comet) with an ancient Greek looking with something that looks like a telescope. See the Image (Thanks to a visitor who provided the link to this image)

Democritus said that the Milky way is a collection of a very large number of stars. Did he observe these starts and if yes how?

Glass-making was known to the ancient Egyptians. The Greeks made small bottles by winding threads of molten colored glass onto a core of clay mixed with manure, then scoring the still-soft glass with a knife to smear the colors, much the way one might with cake frosting. By Roman times, clear glass was available in sufficient quantity and cheaply enough that even common people could afford it. At about the same time, glass- blowing was also invented, further driving down the cost of glass vessels. Austen Layard found that around 3000 BC people in Africa, Asia and the Middle East produced glass that probably was used as jewelry and in this way various optical phenomena were observed. These could be used also for magnification (Layard lenses).

Archimedes used parabolic mirrors to burn ships and Gajus Plinius (23-79 AD) described the magnification properties of a water filled spherical glass container and the law of Snellius was also known.

The Roman Emperor Claudius Nero used a faceted emerald to correct his near-sightedness (remember Sir Peter Ustinov in Quo Vadis) and some examples of glass-crystal lenses were found at Pompeii and Herculaneum.

When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put childish ways behind me. Now we see but a poor reflection as in a mirror; then we shall see face to face.
Paul , 1 Corinthians 13

Nowadays we would say something is clear as glass or that a still lake looked like a mirror. It was a lot different 2000 years ago. Writing about our spiritual ignorance Paul describes the poor reflection of the mirrors of his time. The quote is revealing; ancient mirrors were polished metal with uneven surfaces and imperfect finish and so probably ancient glass was clear enough to transmit light but not to see through sharply. But was this always the case? There are no proofs that optical instruments were really used and that the quality of the glass was sufficiently enough to be used for this purpose.

Hipparchus shown here with a telescope and other astronomical instruments.

H. Thiersch: Pharos, Antike Islam und Occident – Ein Beitrag zur Architekturgeschichte; B. G. Teubner, Leipzig und Berlin 1909, a German book about the Pharos of Alexandria describing the possibility that it was also used as a telescope. Ibn Khordadhbeh writes in the 9^th century AD that one could see even people in Constantinople looking from the telescope of the Pharos.

From the book "Ancient Inventions" by Peter James & Nick Thorpe, published by Ballantine Books in 1994

In 1853 Sir Austen Layard returned from his excavations at Nimrud, one of the capitals of the ancient kingdom of Assyria in northern Iraq. One treasure he brought back with him was a small oval piece of polished rocky crystal, about on-quarter inch thick, in the shape of the lens with one flat surface and one convex, which he had found among a collection of glassware of the ninth to seventh centuries B.C. Layard consulted Sir Davis Brewster, a famous physicist and specialist in optics, who pronounced the object could have been used "either for a magnifying or for concentrating the rays of the sun." Layard noted, "Its properties would scarcely have been unknown to the Assyrians and consequently we have the earliest known specimen of the burning and magnifying glass."

The lens from Nimrud is not an isolated example. Similar rock crystal lenses have turned up in archaeological excavations throughout the Mediterranean and Near East. Two lenses of optical quality are on display at the Heraklion Museum of ancient Cretan civilization. As many as fifty were reported as having been found in the excavations of Troy, though only a handful have been properly published.

Some lenses from these sites have impressive magnifying powers. One lens, probably of the fifth century B.C., found in Crete, can magnify with perfect clarity up to seven times. If it is held farther away from the object viewed, it will actually magnify up to twenty times, though with considerable distortion.

In his house he had a large looking-glass, before which he would stand and go through his exercises., Plutarch Demosthenes

Written by Robert Temple

I was surprised as I strolled through the museums of the world and saw ancient lenses on public display labelled as all kind of crazy things – as anything but lenses! When I went to study ancient Greek lenses in the Department of Classical Antiquities at the British Museum, I met one member of the staff who insisted that there never were any ancient Greek lenses.

(This is despite the fact that Aristophanes describes one in his play The Clouds, and there are countless ancient references to optical technology in the ancient literature) I then proceeded to photograph and measure some ancient Greek lenses in that very room, which the person concerned refused to acknowledge, and I thought more than a little ironic that there is a display cabinet standing just outside the door to the room containing ancient Greek lenses mis-labeled as ‘counters’, and which can be seen clearly magnifying the strands of the cloth underneath them.

When I was in the Athens Archaeological Museum studying Mycenaean lenses, which were clearly on display in the Mycenaean Room (where they are mis-labeled), I could not help but be aware that a former Deputy Director of the same museum had written an article about an apparent crystal lens which he had himself excavated on Crete, but he neglected to mention in his article that his own museum had many such lenses in display cabinets which anyone could walk into the museum and see on any day of the week.

Ancient lenses tended to be of rock crystal until Carthaginian and Roman times, beginning about the 4th century BC, after which glass lenses became more common (being much cheaper), and crystal lenses then became rare.

I discovered significant numbers of ancient British lenses, mis-cataloged in mineral collections; they had been moved to geological museums from their original archaeological collections and were thought to be ‘crystal specimens’! Some of them were most ingenious, and had what I called ‘resting-points’ protruding from their backs so that they could rest on a surface and an artisan could reach his cutting tool round the back and have both hands free for his work. In ancient Troy, one crystal lens excavated by Schliemann had a hole in the center. Some people thought this was an argument for claiming that the lens in question was ‘useless’ because it was perforated in the middle and thus clearly no lens. However, the hole in the center in no way interferes with the magnification, and offers an extremely clever way for an artisan to insert his cutting tool directly through the middle of the magnifier, and have magnification of his work all around it in a circle!

Schliemann excavated about 48 crystal lenses at Troy, but these all disappeared during the Second World War, and all that remained were catalogue descriptions and a single photo of four of the lenses in a group.

I tried for many years to find these missing lenses, and a friend who various times approached the museum in East Berlin where the lenses were last known to have been stored was repeatedly lied to and told that the lenses had ‘been destroyed by Allied bombing in the War’. But of course all this was complete rubbish. When the truth finally came out about the missing Trojan gold hoard found by Schliemann, and that the Red Army had seized it and taken it back to Russia, I suspected the lenses were probably with the gold. And indeed they were. But I have never been granted access to them; the Russians are afraid the Germans will claim them back, and so they won’t let scholars have normal opportunities to study them.

...On the cover of my book Crystal Sun, there is a photo I took of a fragment of a Greek pot from the 5th century BC, which was excavated near the Acropolis in Athens; showing a Greek looking through a telescope. Well now this has been on public display for about 20 years in the Acropolis Museum in Athens. Millions of people have filed past it. Nobody has paid the slightest attention to it, and yet it's obviously a Greek looking through a telescope. What else can it be?

Sines George and Sakellarakis Yannis, Lenses in Antiquity, American Journal of Archaeology 1987.

Note

The word telescope was invented by Demiscianus, a greek scholar. Federigo Cesi, founder of the Accademia dei Lincei asked Demiscianus for a name of the optical instrument and Demiscianus used the world tele "far" and skopeuein "to see" from which the word telescope is derived.

Remarkable Old Kingdom Lenses and the Illusion of the Following Eye