History Forum / General / What If / July 2008

On Jul 6, 1:10 pm, "Anthony Buckland"
<anthonybucklandnos...@telus.net> wrote:

I pulled this out of an Internet google book of which I have a copy,

Lost Optics

Because of a lack of clear literary references, it has often been
denied
that classical Antiquity used lenses to magnify images. (Such lenses
must
be made of better-quality glass, or else crystal, and require better
grinding
techniques, than those used to start res.) But today it seems very
likely
from the archeological evidence that magnifying glasses were indeed in
use. Archeologists have found lenticular objects at many sites,
including
Tyre, Pompeii, Cnossos and the Fayyum.12 Although the nds at Pompeii
page 300
(which started coming up in the eighteenth century) and some other
sites
have often been interpreted as jewelry, and some others were probably
lenses used for ignition, the especially high quality of some of the
lenses
found recently leaves little room for doubt that they were magniers.
One
of two plano-convex lenses found in Crete in 1983, for instance,
magni-
es well at least seven times and still has visible signs of polishing.
13 The
Archeological Museum in Heraklion, Crete, has 23 lenses on display,
some
of prime quality, and has others in storage. Some of the nds, like
the ones
from Cnossos, go back to the bronze age and show that lens technology,
though completely lost in early medieval Europe, is in fact very old.
To accept the idea that magnifying glasses were used in Antiquity we
must account for the scarceness of literary references. We have seen
that
literary sources fail to mention other technological products that
existed
for sure. Also we can imagine that the use of magniers was conned to
a
few fortunate souls: probably some professionals to whom they would be
of most help, such as ne engravers and jewelers,14 and the very rich.
Nero
and his famous emerald monocle may be a case in point.15 Moreover the
lack of literary references to magniers may to some extent derive
from page 301
the beliefs of modern scholars: a person convinced that something did
not
exist in Antiquity cannot but misunderstand any passage mentioning
that
thing. Thus, Alcaeus wrote that wine is a man's dioptron.16 He
probably
meant that drink as it were magnies a person's behavioral traits,
putting
them in evidence,17 but the belief that lenses were unknown has caused
dioptron to be translated as “mirror”, sacricing both the general
sense of
the passage and the natural meaning of the word, which on etymological
grounds can be presumed to mean something that is seen through
(whereas
a mirror is katoptron). Strabo uses the same word to refer to chunks
of a
transparent mineral exported from a certain place in Asia Minor.18

While the ancient use of lenses for lighting res is certain and that
of
magnifying glasses seems at least very probable, few have been willing
to
entertain the possible existence of telescopes in Antiquity. But, if
nothing
else, this hypothesis would explain the many written and pictorial
medieval
references to an object that supposedly would not be invented for
several centuries yet!19 As more direct evidence we may cite a passage
in
Strabo mentioning “reeds” or “tubes” by means of which images can be
magnied thanks to the refraction of visual rays,20 and perhaps also
one in
Geminus explaining that experts in geodesy, who used the dioptra,
based
some of their work on the phenomenon of refraction.21
The conjecture that dioptras provided with lenses—in essence,
telescopes
—were known in the Greek world may seem very daring, but the
possibility would become less far-fetched if there were conrmation
for
the suggestion of Giovanni Pettinato that such instruments were
already
used by Mesopotamian astronomers in the Late Assyrian period.22
Hipparchus was an expert in dioptrics, in that he perfected and
described
dioptras23 and probably already knew the instrument described
by Heron.24 It is not inconceivable that he found a way to apply
knowledge
about refraction to the dioptra.

3Diogenes Laertius, Vitae philosophorum, VI §152.
4For example, De facie quae in orbe lunae apparet, 921A; De Iside et
Osiride, 358F–359A.
5Lucretius, De rerum natura, II:799–800.
6Seneca, Naturales quaestiones, I, vii §1. The passage mentions a
glass virgula, a term that is usually
translated “little rod”. But virga, besides rod, is also the name of
the mini-rainbow that arises
as a result of dispersion, and which Seneca discusses in the
continuation of the passage cited. Thus
virgula vitrea could have been, in Seneca's source, a small straight
rainbow obtained with a glass
object. As to the “many angles”, it is possible that Seneca's source
did not refer to objects with
particularly many facets, but to the refraction angles of the various
colors.
7Apuleius, Apologia, xvi.
8Ptolemy, Optics, V = 223–269 (ed. Lejeune). The work breaks off in
the middle of this book V.
See page 64 for a discussion of Ptolemy's tables of refraction angles.
9Aristophanes, Clouds, lines 766–772.
10Theophrastus, De igne, fr. 73 (Gerke). The fragment actually talks
about lighting a re by converging
sun rays, and it's not totally clear whether a mirror or a lens is
meant; but since both glass
and metals (bronze and silver) are mentioned, Theophrastus probably
has in mind both possibilities.
11Pliny, Naturalis historia, XXXVII §§28–29.
Revision:
12See [Beck] for the Cnossos nd. The scant literary evidence is
discussed in [Kisa], vol. II,
pp. 357–359.
13[Sines, Sakellarakis]. This article also discusses other recent nds
and some older ones.
14Already in the eighteenth century the jewelry carver Johann Natter,
based on his study of
ancient techniques, became convinced that his ancient colleagues could
not have carried out all of
their work with the naked eye; see [Natter]. The same opinion is held
today by several scholars
based on an analysis of gold craftmanship, particularly in the Roman
period; see [Sines, Sakellarakis].
15Pliny, Naturalis historia, XXXVII §64. This continues a passage
where Pliny mentions that engravers
used emeralds to lessen eye-strain and provide bigger images; but
Pliny believed that the
engravers rested their eyes by contemplating the emeralds and that the
enlarged images were those
of the emeralds themselves.
16 
    
            􀀀
    
(Alcaeus, fr. 333 Voigt).
17I am indebted to Bruno Gentili for this observation.
18Strabo, Geography, XII, ii §10.
Revision: 1.16 Date: 2003/08/10 22:00:00
19See page 306.
20Strabo, Geography, III, i §5. Many editors have adopted Voss's
emendation of
􀀀


(reeds) into
 
(glass pieces), thus admitting the existence of magnifying glasses
but perhaps missing the
full import of the passage.
21In [Heron: OO], IV, 100:17–18. The Greek term 


􀀀
 is usually rendered as “reection”,
but there are several passages where “refraction” must be meant: for
example, Sextus Empiricus,
Adversus astrologos ( = Adv. math. V), §82. Both this and the
complementary word
􀀀
 

􀀀
 seem
to have been used for both phenomena, the choice apparently depending
on whether the light rays
are broken upwards or downwards (their root is
  , “break”).
22[Pettinato], p. 103.
23Ptolemy mentions the use of optical devices by Hipparchus and his
written description of
a dioptra (Almagest, V, v, 369; V, xiv, 417, ed. Heiberg). Pliny
mentions Hipparchus' contribution
to the perfecting of optical instruments for astronomical observations
(Naturalis historia, II §95).
The precision of the optical instruments used by Hipparchus and in
particular the accuracy of his
angular measurements can be gauged from the excellent approximation of
his measurement of the
distance to the moon (see note 95 on page 80).
24So Toomer in [Ptolemy/Toomer], p. 227, note 20. The suspicion that
on this subject Heron may
have used Hipparchus as his source is suggested by the fact that the
method described by Heron
in the Dioptra for determining the longitudinal difference between
Alexandria and Rome, based on
the difference in local time for the same lunar eclipse, had been
proposed by Hipparchus, as we
know from Strabo (Geography, I, i §12). But dioptras analogous to the
one Heron describes may be
even older than Hipparchus: the thesis that they were already in use
in the early third century is
expounded in [Goldstein, Bowen].

The forgotten revolution: how science was born in 300 BC and why it
had to be reborn, Lucio Russo
http://books.google.com/books?id=MOTpnfz7ZuYC&pg=PT286&lpg=PT286&dq=lucio+russo+
the+use+of+lenses+to+focus+sun+rays+is+documented&source=web&ots=NI_H5NYX79&sig=
tumEDubeMfAmZ_LDx6rnuDvOP6k&hl=en&sa=X&oi=book_result&resnum=1&ct=result
pp270 ff

another example of ancient lenses, this time a telescope:

World's oldest telescope?

Is this the oldest telescope lens in the world?

By BBC News Online Science Editor Dr David Whitehouse

If one Italian scientist is correct then the telescope was not
invented sometime in the 16th century by Dutch spectacle makers, but
by ancient Assyrian astronomers nearly three thousand years earlier.

BBC News' Dominic Hughes: This could mean that the telescope was
invented two and a half thousand years earlier

According to Professor Giovanni Pettinato of the University of Rome, a
rock crystal lens, currently on show in the British museum, could
rewrite the history of science. He believes that it could explain why
the ancient Assyrians knew so much about astronomy.

But experts on Assyrian archaeology are unconvinced. They say that the
lens is of such low quality that it would have been a poor aid to
vision.

Magnifying glass

It is called the Nimrud lens and it was found in 1850 by the legendary
archaeologist Sir John Layard, during an epic series of excavations at
the palace of Nimrud in what is now Iraq.

[ image: Trinket or telescope?]
Trinket or telescope?
Upon his return to England, he showed the lens to physicist Sir David
Brewer who thought it could have been used as a magnifying glass or to
concentrate the Sun's rays.

Used as a magnifying glass, it could have been useful to Assyrian
craftsman who often made intricate seals and produced minuscule texts
on clay tablets using a wedge-shaped script.

It is a theory many scientists might be prepared to accept, but the
idea that the rock crystal was part of a telescope is something else.
To get from a lens to a telescope, they say, is an enormous leap.

Saturn's serpents

Professor Pettinato counters by asking for an explanation of how the
ancient Assyrians regarded the planet Saturn as a god surrounded by a
ring of serpents?

Could they not have seen Saturn's rings through their telescope and
interpreted them as serpents? An unconvincing argument, say experts.
The Assyrians saw serpents everywhere. And why is it in their many
astronomical reports on clay tablets there is no mention of such a
device?

The conventional understanding of the invention of the telescope is
that it was developed in the 16th century by Dutch spectacle-makers
who held one lens in front of another.

One thing is sure: Galileo did not invent it - a common misconception
- although he was one of the first to turn it towards the sky. By
then, lenses used as spectacles had been known for hundreds of years
at least, and it has been a puzzle to historians why it took so long
for the telescope to be invented.

Commercial and military use

It may have been developed and then forgotten, or even kept secret.
However, experts regard this as unlikely given the commercial and
military uses that a telescope could serve.

[ image: Galileo did not invent the telescope]
Galileo did not invent the telescope
Whatever its origin, as ornament, as magnifying lens or part of a
telescope, the Nimrud lens is the oldest lens in the world. Looking at
it evokes mystery and wonder. It can be seen in room 55 of the British
Museum, in case 9 of the Lower Mesopotamian Gallery

It may not be unique. Another, possibly 5th century BC, lens was found
in a sacred cave on Mount Ida on Crete. It was more powerful and of
far better quality than the Nimrud lens.

Also, Roman writers Pliny and Seneca refer to a lens used by an
engraver in Pompeii. So perhaps the ancients knew more about lenses
than we give them credit for.

http://news.bbc.co.uk/2/hi/science/nature/380186.stm

The really weird one is the microscope, because you can make an
extremely good magnifier with a drop of water or a teeny glass bead. See
e.g. the Leeuwenhoek design which is basically a glass bead fixed behind
a small pinhole. Bead lenses can be made by melting rather than
grinding, a MUCH easier process.

http://en.wikipedia.org/wiki/Leeuwenhoek

There's currently a modern microscope of this type (a toy made in the
1960s-80s) on sale on eBay UK, grossly overpriced at £15 (it's item
number: 310064821363 if anyone wants it). I paid 5s (25p) for one when I
was a kid.

The Greeks beliewed that light came -out- of the eye. Would they have
developed optics?

Bob Kolker

On Jul 6, 10:10 am, "Anthony Buckland"
<anthonybucklandnos...@telus.net> wrote:

With good lens grinding technology a whole host of
phenomenon would open up.

1.  The Heliocentric view is probably going to overturn
the Geocentric view.  New data and more precise
measurements are going to more conclusively
provide more decisive data, and Ptomely is probably
going to get displaced in classical times.  Probably the
incentive to calibrate measurements are going to point
toward the direction of getting more precise data.  Kepler's
laws are probably going to be found as a result.

2.  Later someone might come up with the microscope.
People will find small animacules in water and see a
host of small structures like cells in living organisms.
Eventually someone might come up with the germ theory
of disease to combat the theory of 'humors' as an offshoot
of direct observation.  Someone might even look at fossils
with a microscope and by inference decide that they are
very old animals and come up with the idea of a very old
Earth like Buffon in the mid-1700s.

All of these discoveries might be tossed in during the
period of the later decadent Roman Empire.  This is
a rather interesting idea, and it is difficult to predict
how the lines of thought in classical would would have
changed as a result.

It is notable, however, how much later the telescope
came into existence in comparison with earlier lens
grinding technology.

Reasonably, however, it seems more than feasible
that it could have had as much impact, as Roman
steam as advanced as that which existed in Europe
and America in the early 1800s would have had, and
in practice, it would have been much easier to do.

    The first microscope was an oil drop.

    As others have pointed out they likely did exist. So the question becomes why
did nothing interesting happen.

    I have been on the pro-lens side in past discussions. Clearly the cabochon
cut for stones existed and once it is done with quartz you have a lens.

    So a re-examination of the lenses in museums is in order.

    I would guess the problem is in the cost of quartz lenses and in the problem
of not having transparent glass. Lenses were expensive because they were of
natural crystals and cheap lenses of glass with the clarity our lenses did not
exist.

    So the bottom line is looking into what it took to create something like our
quality glass.