The first telescope?

Damian Burrin wrote:
what was the first telescope?

Galileo invented the telescope in 1609 it was a refractor, Newton intented
the reflector scope but i forget when.

That is wrong in every important respect:
* The first telescope, a catadioptric, was probably invented by Leonard
Digges, before 1561 (which is the earliest mention of it).
* Thomas Harriot, a tutor of Walter Raleigh, drew a telescopic map of
the Moon in 1608, before Galileo obtained his first telescope.
* The refractor was made by Hans Lippershey in 1608
* The reflector was invented by James Gregory in 1663
* Newton made his reflector in 1668



Best,
Stephen

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what was the first telescope? or is it unknown for sure. was it a refractor?
presumably its not in existance now.

what was the first telescope?

Galileo invented the telescope in 1609 it was a refractor, Newton intented
the reflector scope but i forget when.

Damian

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UKRA 1159 Level 2 RSO
EARS 1115
http://www.ukrocketry.com
http://www.larf-rocketry.co.uk

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"simon.coombs3" wrote in message
...
what was the first telescope? or is it unknown for sure. was it a
refractor?
presumably its not in existance now.

In message , Stephen Tonkin
writes
Damian Burrin wrote:
what was the first telescope?

Galileo invented the telescope in 1609 it was a refractor, Newton intented
the reflector scope but i forget when.

That is wrong in every important respect:

Good enough for GCSE in Astronomy, then.

"simon.coombs3" wrote in message
...
what was the first telescope? or is it unknown for sure. was it a
refractor?
presumably its not in existance now.



As well as this piece from NS I seem to remember archaeoligists finding a
pair of felspar slivers in close
proximity at a Viking site. The speculation was they would have been housed
in a wooden tube ,
mutually rotatable and acting as a solar polariscope for guaging time at sea
even when overcast.

New Scientist vol 160 issue 2159 - 07 November 1998, page 25
Vikings were surprisingly well focused

STUDIES of Viking lenses suggest their makers could have taught modern
optometrists a thing or two. Quartz lenses made around one thousand years
ago have optical properties that match modern standards.

Aspheric lenses, which have an elliptical shape, are commonly used in
spectacles and cameras. The equations describing their optical properties
are thought to have been devised by the French philosopher and mathematician
René Descartes in the 17th century. But he could not find anyone skilful
enough to make one.

Yet now it seems the Vikings were making them hundreds of years earlier.
Optics specialists led by Olaf Schmidt of the University of Applied Science
in Aalen, Germany, have studied Viking lenses from museums in Munich and
Sweden. They found their shapes closely matched an ellipse. The optical
qualities of some of the best examples were comparable to modern lenses. "If
you look at the shape of the lenses they are remarkably smooth," says
Schmidt.

Schmidt believes the lenses were made on a simple lathe and used for
focusing sunlight to light fires and cauterise wounds. How Viking craftsmen
discovered the optimum shape remains a mystery. "I think it's very unlikely
they understood the mathematics of the lenses," says John Bell, editor of
Opto & Laser Europe.

Duncan Graham-Rowe

source:
http://archive.newscientist.com/secu...1&id=mg1602159
3.900

My conjecture is you don't need carefully crafted lenses to start fires.

Humour of the streets
http://www.divdev.fsnet.co.uk/graff.htm

* The first telescope, a catadioptric, was probably invented by Digges,
before 1561

From Nineplanets.org

English scholars Robert Recorde (1551) and Leonard Digges (1571) refer to
use of "perspective glasses" to view distant objects, while Digges discusses
mirrors being used similarly. William Bourne (1585) and Giambattista Della
Porta (1589) claimed to have discovered a way to use two lenses to view
distant objects, but neither manufactured a telescope.

Controversy over the Invention of the Refracting Telescope
Dutch spectacle maker Hans Lippershay filed a patent application in Holland
on October 2, 1608, requesting exclusive rights to make and distribute "an
instrument for seeing at a distance", consisting of a weak positive
objective lens and a strong negative eyepiece. Lippershay constructed a
telescope on request and was tested successfully; he received an initial
contract for construction of up to three instruments.

Dutch spectacle maker Jacob Adriaanzoon filed a counterpetition, claiming he
had constructed a telescope of power equal to Lippershay's and would
construct one if he were paid to do it. Given the success in dealing with
Lippershay, the Dutch authorities declined to pay for the construction.

Dutch spectacle maker Zacharias Jansen claimed to have invented the
telescope prior to Lippershay and that the latter should not be granted an
exclusive manufacturing patent. Despite a lack of evidence for prior
invention from Adriaanzoon and Jansen, the Dutch government decided the
issue too confused and refused to grant Lippershay's application.







--
Damian Burrin
UKRA 1159 Level 2 RSO
EARS 1115
http://www.ukrocketry.com
http://www.larf-rocketry.co.uk

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"Stephen Tonkin" wrote in message
...
Damian Burrin wrote:
what was the first telescope?

Galileo invented the telescope in 1609 it was a refractor, Newton
intented
the reflector scope but i forget when.

That is wrong in every important respect:
* The first telescope, a catadioptric, was probably invented by Leonard
Digges, before 1561 (which is the earliest mention of it).
* Thomas Harriot, a tutor of Walter Raleigh, drew a telescopic map of
the Moon in 1608, before Galileo obtained his first telescope.
* The refractor was made by Hans Lippershey in 1608
* The reflector was invented by James Gregory in 1663
* Newton made his reflector in 1668



Best,
Stephen

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I'm sure this was a question on QI, with Galileo being an 'obvious' answer


Larry

"Stephen Tonkin" wrote in message
...
Damian Burrin wrote:
what was the first telescope?

Galileo invented the telescope in 1609 it was a refractor, Newton
intented
the reflector scope but i forget when.

That is wrong in every important respect:
* The first telescope, a catadioptric, was probably invented by Leonard
Digges, before 1561 (which is the earliest mention of it).
* Thomas Harriot, a tutor of Walter Raleigh, drew a telescopic map of
the Moon in 1608, before Galileo obtained his first telescope.
* The refractor was made by Hans Lippershey in 1608
* The reflector was invented by James Gregory in 1663
* Newton made his reflector in 1668



Best,
Stephen

Remove footfrommouth to reply

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Very interesting. My view is that just as the likes of Ross and Herschel
checked the accuracy of their optics pragmatically, by seeing how good the
image was, the vikings in your story might have done likewise. Victorian and
before optics are generally appalling when tested with modern equipment, but
there is no question that they achieved better than spherical
approximations.


Brian



"N Cook" wrote in message
news

"simon.coombs3" wrote in message
...
what was the first telescope? or is it unknown for sure. was it a
refractor?
presumably its not in existance now.



As well as this piece from NS I seem to remember archaeoligists finding a
pair of felspar slivers in close
proximity at a Viking site. The speculation was they would have been
housed
in a wooden tube ,
mutually rotatable and acting as a solar polariscope for guaging time at
sea
even when overcast.

New Scientist vol 160 issue 2159 - 07 November 1998, page 25
Vikings were surprisingly well focused

STUDIES of Viking lenses suggest their makers could have taught modern
optometrists a thing or two. Quartz lenses made around one thousand years
ago have optical properties that match modern standards.

Aspheric lenses, which have an elliptical shape, are commonly used in
spectacles and cameras. The equations describing their optical properties
are thought to have been devised by the French philosopher and
mathematician
René Descartes in the 17th century. But he could not find anyone skilful
enough to make one.

Yet now it seems the Vikings were making them hundreds of years earlier.
Optics specialists led by Olaf Schmidt of the University of Applied
Science
in Aalen, Germany, have studied Viking lenses from museums in Munich and
Sweden. They found their shapes closely matched an ellipse. The optical
qualities of some of the best examples were comparable to modern lenses.
"If
you look at the shape of the lenses they are remarkably smooth," says
Schmidt.

Schmidt believes the lenses were made on a simple lathe and used for
focusing sunlight to light fires and cauterise wounds. How Viking
craftsmen
discovered the optimum shape remains a mystery. "I think it's very
unlikely
they understood the mathematics of the lenses," says John Bell, editor of
Opto & Laser Europe.

Duncan Graham-Rowe

source:

http://archive.newscientist.com/secu...1&id=mg1602159
3.900

My conjecture is you don't need carefully crafted lenses to start fires.

Humour of the streets
http://www.divdev.fsnet.co.uk/graff.htm




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"Brian" wrote in message ...
Very interesting. My view is that just as the likes of Ross and Herschel
checked the accuracy of their optics pragmatically, by seeing how good the
image was, the vikings in your story might have done likewise. Victorian and
before optics are generally appalling when tested with modern equipment, but
there is no question that they achieved better than spherical
approximations.


Brian




I was a bit rushed when I extracted the piece from
the NS archive and posted.
I meant to also say that for cauterising,
they would have used a red-hot poker or
hot tar - focusing the sun is a bit far-fetched.
The ther point is the archaeological context.
I cannot find citation of the felspar cross-
polarizers but they were found close together
suggesting a pair used together. A lot
depends on how the Viking lenses were found;
single, pairs, pair lad out as specs or pairs
laid out as scope.

"N Cook" wrote in message ...

STUDIES of Viking lenses suggest their makers could have taught modern
optometrists a thing or two. Quartz lenses made around one thousand years
ago have optical properties that match modern standards.


Yet now it seems the Vikings were making them hundreds of years earlier.
Optics specialists led by Olaf Schmidt of the University of Applied Science
in Aalen, Germany, have studied Viking lenses from museums in Munich and
Sweden. They found their shapes closely matched an ellipse. The optical
qualities of some of the best examples were comparable to modern lenses. "If
you look at the shape of the lenses they are remarkably smooth," says
Schmidt.

Schmidt believes the lenses were made on a simple lathe and used for
focusing sunlight to light fires and cauterise wounds. How Viking craftsmen
discovered the optimum shape remains a mystery. "I think it's very unlikely
they understood the mathematics of the lenses," says John Bell, editor of
Opto & Laser Europe.

Duncan Graham-Rowe

The Vikings had a range or remarkable skills. Not least their
shipbuilding and jewellery. The skills and materials involved in
working & polishing gold and silver cannot have been lost on these
early opticians. Their raw materails may have come from volcanic
Iceland or Norway.

A vertical "potters wheel" or pole lathe using resin to hold the lens
to a rotating device is not rocket science.
The use of natural tar or resins as a polishing lap with whatever
polishing media was available would no doubt provide a high polish.
Cloth (or paper?) would also function as polishing tool coverings. It
may be that they used very long, slow polishing methods which
contributed to the high polish and asphericity.

Given enough time the skills would be raised to a high standard. There
was some suggestion that the lenses may have come from Arabia. Though
I can't see why that should be necessary. Given the extraordinary
skills shown by the Vikings in other fields.

Localised polishing can be achieved by degrees of overhang. Or
stroking of polishing tools in well rehearsed movements. Such
localised polishing could be deliberate or quite accidental.

I am surprised to hear that Victorian lenses were so poor. I had the
pleasure of watching elderly optical workers with decades of
experience. Shaping and polishing unusual spectacle lenses on simple
vertical spindles. The chosen cast-iron tool rotated on the tapered
spindle in a round vertical drum. Which collected the abrasive that
flew off the work.

A hand-controlled over-arm with an adjustable downward-pointing pin
held the back of the lens via a lacquered or pitched on back plate.
Which allowed the lens to spin freely on the tool under the pin. The
skills of these men had to be seen to be appreciated. No lens gave
them a moment's pause. Their movements were totally instinctive
whether the lens was a small convex "pebble", completely flat or as
deep as an egg cup. The polish achieved was very transparent compared
with the machine-made lenses using the same paper polishing pads and
cerium oxide.

There is no reason why a Viking craftsman with a similar machine
(however crude) could not develop a polishing routine over many years
which offered a near perfect finished product.
Any asphericity may have been a direct result of the methods, tools or
materials used. It may be that the natural crystals they used in lens
making had differing hardness. Depending on the axis of crystal being
polished.

Using a crude analogy: If the crystal were a piece of wood: It is
possible that the "grain" of the material was always chosen to be at
right angles to the lens axis. Or the crystal was always formed in
such a way that a lens would always be made from the largest diameter.
Which always coincided with the crystal's natural grain orientation.
The centre of the lens might have different qualities to the
"shoulders" which would be "end grain" (in the crude 'wood' analogy)
The centre of the lens would polish away relative to the
harder-to-polish "shoulders" & edges. Resulting automatically in an
elipsoid of revolution. But I have no experience whatsoever of the
materials involved and may be quite mistaken as to a "grain" being
present in these rock crystals.

Chris.B