Roman telescope

I am writing a what-if history fiction and need some help.

If you were suddenly dropped in Rome say in 200 CE and you needed to
build a telescope for mass production. What sort of telescope would you
make and what would it look like?











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How many public servants care enough about their department agenda that
they would be willing, if it received a budget cut to take a pay cut?

Observations of Bernard - No 46

Bernardz wrote:

I am writing a what-if history fiction and need some help.

If you were suddenly dropped in Rome say in 200 CE and you needed to
build a telescope for mass production. What sort of telescope would you
make and what would it look like?

You would essentially be limited to what Galileo used centuries later, a
very basic refractor telescope using one convex objective lens, perhaps
an inch (25mm) in diameter and a smaller concave eyepiece lens located
at the focal length of the objective. The lenses would be assembled in a
metal or paper tube. The hard part would be making optical quality glass
in 200-CE. It took about 5000-years from the accidental discovery of
glass by the Phoenicians, (in the sand under their cooking fires) to the
first lenses in the 16th century. You would need a small blast furnace
to make the glass from sand. Each lens would be shaped by grinding two
glass disks together with some natural abrasive (sand?) and water
between them. The abrasive would have to be graded to various sizes by
letting it settle through a water column. You would start the grinding
with the coarse grade and proceed to the finest, just like it's done
today. Finally the lens would be polished, probably using bees wax to
make a 'lap' with some kind of very fine abrasive or 'rouge' as the
polishing agent, which might be hard to find in that era.
In all, it would be a very challenging project and I doubt it would be
practical to mass produce them. However, even if you made just one
telescope in Roman times it could change the course of history.


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On Sun, 22 Feb 2004 09:37:58 -0500, starman wrote:

You would essentially be limited to what Galileo used centuries later, a
very basic refractor telescope using one convex objective lens, perhaps
an inch (25mm) in diameter and a smaller concave eyepiece lens located
at the focal length of the objective...

That's not what I'd build if I were dropped into that period of history. I'd
make a Newtonian reflector. It would be quite practical to build one 4-6 inches
in aperture using commonly available materials. The quality of the glass can be
much lower with a reflecting telescope, and there is less glass grinding
required. The only lens would be the ocular- much smaller than a refractive
objective.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

That's not what I'd build if I were dropped into that period of history. I'd
make a Newtonian reflector. It would be quite practical to build one 4-6
inches
in aperture using commonly available materials. The quality of the glass can
be much lower with a reflecting telescope, and there is less glass grinding
required. The only lens would be the ocular- much smaller than a refractive
objective.

A Newtonian was my first thought but silvering the mirror seemed like the real
problem. Newtonian mirrors were metal until sometime in the 1800's...

I guess one could make a silver Newtonian mirror.

I don't expect to hear from uncle Rod on this one, pretty difficult to make an
SCT in 200BC...

jon

On 22 Feb 2004 15:37:14 GMT, Jon Isaacs wrote:

That's not what I'd build if I were dropped into that period of history. I'd
make a Newtonian reflector. It would be quite practical to build one 4-6
inches
in aperture using commonly available materials. The quality of the glass can
be much lower with a reflecting telescope, and there is less glass grinding
required. The only lens would be the ocular- much smaller than a refractive
objective.

A Newtonian was my first thought but silvering the mirror seemed like the real
problem. Newtonian mirrors were metal until sometime in the 1800's...

When a simple (though messy) chemical process was figured out to deposit
silver.

If you know this process (basically, silver nitrate, ammonia, and glucose
are all that's required), it would be possible to duplicate it with the
materials available at the time (increasing human knowledge of chemistry
at the same time).

I guess one could make a silver Newtonian mirror.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology), such a mirror would be lighter, stronger, and more
resistant to tarnish and corrosion.

But all metal mirrors would suffer from expansion issues. It would be
more practical to work out the silvering process.

I don't expect to hear from uncle Rod on this one, pretty difficult to make an
SCT in 200BC...

Yes, the corrector would be quite a challenge. A MCT, however, might just
be doable, though still quite difficult (and it would require the ability
to silver glass, unless an independant secondary design were used).


--
- Mike

Remove 'spambegone.net' and reverse to send e-mail.

If you know this process (basically, silver nitrate, ammonia, and glucose
are all that's required), it would be possible to duplicate it with the
materials available at the time (increasing human knowledge of chemistry
at the same time).

Do you know how to make Silver Nitrate and extract purify Glucose and purify
ammonia?? Or did the Romans already know of Silver Nitrate.....But my guess is
that they did not.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology),

Aluminum does

Before the 1850's aluminum was more expensive than Gold or Silver. I don't
think the processes required to produce aluminum in sufficient quantities for a
mirror would be possible...

Here is a quote from http://www.world-aluminium.org/history/

"""1854 Henri Sainte-Claire Deville (France) improves Wöhler's method to create
the first commercial process. The metal's price, initially higher than that of
gold and platinum, drops by 90% over the following 10 years. The price is still
high enough to inhibit its widespread adoption by industry.

1855 A bar of aluminium, the new precious metal, is exhibited at the Paris
Exhibition.

1885 Hamilton Y. Cassner (USA) improves on Deville's process. Annual output 15
tonnes!

1886 Two unknown young scientists, Paul Louis Toussaint Héroult (France) and
Charles Martin Hall (USA), working separately and unaware of each other's work,
simultaneously invent a new electrolytic process, the Hall-Héroult process,
which is the basis for all aluminium production today. They discovered that if
they dissolved aluminium oxide (alumina) in a bath of molten cryolite and
passed a powerful electric current through it, then molten aluminium would be
deposited at the bottom of the bath.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology),

Aluminum does not exist naturally, it was not discovered until 1808.

"Aluminium is the third most abundant element in the Earth's crust and
constitutes 7.3% by mass. In nature however it only exists in very stable
combinations with other materials (particularly as silicates and oxides) and it
was not until 1808 that its existence was first established. It took many years
of painstaking research to "unlock" the metal from its ore and many more to
produce a viable, commercial production process."

http://www.world-aluminium.org/history/
----

My money still rests on making a mirror from a material known at the time like
silver, gold or bronze. The Romans had mirrors which glass with silver or gold
foil coated but as someone pointed out, that would probably not be sufficient.

Trying to develop a silvering process would most likely mean developing the
chemical industry to manufacture the chemicals needed and personally i don't
know enough chemisty to do that.

jon

If you know this process (basically, silver nitrate, ammonia, and glucose
are all that's required), it would be possible to duplicate it with the
materials available at the time (increasing human knowledge of chemistry
at the same time).

Do you know how to make Silver Nitrate and extract purify Glucose and purify
ammonia?? Or did the Romans already know of Silver Nitrate.....But my guess is
that they did not.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology),

Aluminum does

Before the 1850's aluminum was more expensive than Gold or Silver. I don't
think the processes required to produce aluminum in sufficient quantities for a
mirror would be possible...

Here is a quote from http://www.world-aluminium.org/history/

"""1854 Henri Sainte-Claire Deville (France) improves Wöhler's method to create
the first commercial process. The metal's price, initially higher than that of
gold and platinum, drops by 90% over the following 10 years. The price is still
high enough to inhibit its widespread adoption by industry.

1855 A bar of aluminium, the new precious metal, is exhibited at the Paris
Exhibition.

1885 Hamilton Y. Cassner (USA) improves on Deville's process. Annual output 15
tonnes!

1886 Two unknown young scientists, Paul Louis Toussaint Héroult (France) and
Charles Martin Hall (USA), working separately and unaware of each other's work,
simultaneously invent a new electrolytic process, the Hall-Héroult process,
which is the basis for all aluminium production today. They discovered that if
they dissolved aluminium oxide (alumina) in a bath of molten cryolite and
passed a powerful electric current through it, then molten aluminium would be
deposited at the bottom of the bath.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology),

Aluminum does not exist naturally, it was not discovered until 1808.

"Aluminium is the third most abundant element in the Earth's crust and
constitutes 7.3% by mass. In nature however it only exists in very stable
combinations with other materials (particularly as silicates and oxides) and it
was not until 1808 that its existence was first established. It took many years
of painstaking research to "unlock" the metal from its ore and many more to
produce a viable, commercial production process."

http://www.world-aluminium.org/history/
----

My money still rests on making a mirror from a material known at the time like
silver, gold or bronze. The Romans had mirrors which glass with silver or gold
foil coated but as someone pointed out, that would probably not be sufficient.

Trying to develop a silvering process would most likely mean developing the
chemical industry to manufacture the chemicals needed and personally i don't
know enough chemisty to do that.

jon

"Mike Ruskai" wrote in
.earthlink.net:


Why not one made of aluminum? Though sufficient quantities of
aluminum would be challenging to find (and impossible to refine from
ore with existing technology), such a mirror would be lighter,
stronger, and more resistant to tarnish and corrosion.



No way.

First, Aluminum was not even discovered until 1808. The Romans didn't
have it.

Second, virtually no native aluminum metal exists. It is all the oxide
ore.

Third, A bar of aluminum was first exibited in Paris in 1855 and was
about the only sample ever produced until that time. It was very
expensive.

Fourth, the first technique for refining aluminum was not invented until
the 1880s. It requires electricity, and a lot of it, so even if you knew
how it is done it is going to be hard to get the Romans up to speed on
electricity too. The current process requires a LOT of heat.

Fifth, you would still have trouble with aluminum tarnishing because you
could not overcoat the mirror as is done today.

You would be better off working with some metal that the Romans already
knew about.

Bryan

"Mike Ruskai" wrote in
.earthlink.net:


Why not one made of aluminum? Though sufficient quantities of
aluminum would be challenging to find (and impossible to refine from
ore with existing technology), such a mirror would be lighter,
stronger, and more resistant to tarnish and corrosion.



No way.

First, Aluminum was not even discovered until 1808. The Romans didn't
have it.

Second, virtually no native aluminum metal exists. It is all the oxide
ore.

Third, A bar of aluminum was first exibited in Paris in 1855 and was
about the only sample ever produced until that time. It was very
expensive.

Fourth, the first technique for refining aluminum was not invented until
the 1880s. It requires electricity, and a lot of it, so even if you knew
how it is done it is going to be hard to get the Romans up to speed on
electricity too. The current process requires a LOT of heat.

Fifth, you would still have trouble with aluminum tarnishing because you
could not overcoat the mirror as is done today.

You would be better off working with some metal that the Romans already
knew about.

Bryan

On 22 Feb 2004 15:37:14 GMT, Jon Isaacs wrote:

That's not what I'd build if I were dropped into that period of history. I'd
make a Newtonian reflector. It would be quite practical to build one 4-6
inches
in aperture using commonly available materials. The quality of the glass can
be much lower with a reflecting telescope, and there is less glass grinding
required. The only lens would be the ocular- much smaller than a refractive
objective.

A Newtonian was my first thought but silvering the mirror seemed like the real
problem. Newtonian mirrors were metal until sometime in the 1800's...

When a simple (though messy) chemical process was figured out to deposit
silver.

If you know this process (basically, silver nitrate, ammonia, and glucose
are all that's required), it would be possible to duplicate it with the
materials available at the time (increasing human knowledge of chemistry
at the same time).

I guess one could make a silver Newtonian mirror.

Why not one made of aluminum? Though sufficient quantities of aluminum
would be challenging to find (and impossible to refine from ore with
existing technology), such a mirror would be lighter, stronger, and more
resistant to tarnish and corrosion.

But all metal mirrors would suffer from expansion issues. It would be
more practical to work out the silvering process.

I don't expect to hear from uncle Rod on this one, pretty difficult to make an
SCT in 200BC...

Yes, the corrector would be quite a challenge. A MCT, however, might just
be doable, though still quite difficult (and it would require the ability
to silver glass, unless an independant secondary design were used).


--
- Mike

Remove 'spambegone.net' and reverse to send e-mail.