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Nothing worth bothering about on tv



 
 
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  #31  
Old August 23rd 19, 06:48 PM posted to uk.tech.digital-tv
Java Jive[_3_]
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Default Nothing worth bothering about on tv

On 23/08/2019 16:58, tim... wrote:

"Andrew" wrote in message

Jim Al-Kalili's series on inventions is rather good,


But not without unnecessary hyperbole.

"The basic telescope was invented due to a *revolution* in science"

Um no, it came about because someone discovered that they could make
simple optical glass.

Hardly a revolutionary invention.


Actually it was, but you/we tend not to realise it because you/we are
looking back from all that has happened since. The excellent series,
'The Day The World Took Off' AFAICR originally shown on Channel 4 about
15 years ago, examined all the technological strands that went into
Stevenson's Rocket, which they chose arbitrarily to mark the beginning
of the Industrial Revolution, and these strands were surprisingly many
and varied, and included the invention of optical glass.

Optical glass was unknown in other parts of the world which had come up
with many other great inventions, even areas that used glass itself.
There are many possible reasons for this, some of which become
self-evident below, but also it should not be forgotten that making
glass demands a great deal of heat, and therefore is most easily done in
areas that have access to coal, rather than only peat or wood as a fuel ...

The ancient Chinese had porcelain, which is similarly produced, but not
glass. The Japanese, living in a land riven by earthquakes and volcanic
eruptions, had paper windows, not glass. Many people of Asian origin
are born with a tendency to short-sightedness, and the lack of optical
glass to make spectacles, and then later the fact that the lenses to
correct this needed to be concave rather than convex, which are more
difficult to grind accurately, tended to mean that their interests and
art tended to concentrate on things that could be done with the human
eye, and therefore face, very close to the work. AFAICR, glass was
invented or discovered by the Romans, or at least in the Roman era, for
certainly they had glass, and even as late in Renaissance Italy, ornate
glass for drinking vessels was much prized, so much so that it was a
protected industry, and people who had the knowledge of it were not
allowed to leave the area where it was produced, but, again, this was
not optical glass.

Even in northern climes, where optical glass is now used everywhere in
windows, before the Industrial Revolution, the glass used in the windows
of those establishments that could afford them was not made to be
optically perfect enough to make lenses. AFAICR, it was made by
adapting the process already used to make glass vessels, but once a blob
of molten glass had been got onto the blowing tube, the tube was spun
back and forth so that the centrifugal effect spun it into a disk thin
enough to cut up into the small panes that can still be found in leaded
windows. Ironically btw, the centre of the disk was the cheapest piece
to buy because of the thick knob of glass in the middle of it couldn't
be seen through, but now these often have pride of place in the front
windows of pubs and cafes of the 'Ye Olde' variety! But then as now
this process generally produced very optically imperfect glass. Once
optical glass windows became widely available and thus more affordable,
the extra daylight that they transmitted, by highlighting dirt, enabled
a revolution in household cleanliness and therefore improved health for
the inhabitants.

But, to realise just what a revolution optical glass was, just think
what it gives you besides panes for windows, and lenses for spectacles,
microscopes, and telescopes. Though even each of those is very
important, so much so that each could be considered revolutionary in its
own right, there is also the advancement of science that optical glass
enables. You can make glass vessels to perform experiments in, and now
you can see what is happening during the experiment, instead of only
being able to examine the results afterwards. And you can calibrate
these vessels accurately, partly because you can draw out glass into
tubes to transfer fluids between these new glass vessels, and thereby
make such things as condensing coils, again being able to see what is
being collected inside them, but then again because a smallish volume
can be made with one long dimension, you can calibrate these tubes more
accurately in making measurements of volume, and this gives you more
accurate thermometers and barometers, etc. Further, you can make bell
jars, from which you can pump out the air, all the time being able to
watch what happens inside. Etc, etc.

This revolution in glass scientific hardware made possible accurate
measurements of fluids of all types, including water and steam, and thus
provides the accurate scientific data necessary to derive the underlying
laws governing the their behaviour, particularly when subjected to heat.
Hence its relevance to a program examining the invention of the steam
engine and the Industrial Revolution.

Optical glass was indeed a revolution.
  #32  
Old August 23rd 19, 07:09 PM posted to uk.tech.digital-tv
Java Jive[_3_]
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Default Nothing worth bothering about on tv

On 23/08/2019 18:48, Java Jive wrote:

The ancient Chinese had porcelain, which is similarly produced, but not
glass.


Think I may be picked up on that, so to clarify, I meant that both
require a great deal of heat.
  #33  
Old August 23rd 19, 07:56 PM posted to uk.tech.digital-tv
Max Demian
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Default Nothing worth bothering about on tv

On 23/08/2019 17:50, Jim Lesurf wrote:
In article ,
tim... wrote:
Jim Al-Kalili's series on inventions is rather good,


But not without unnecessary hyperbole.


It does also contain some 'blurred' explanations in a few places. Overall,
good though.


He explained the use of cepheid variables to estimate the distance of
stars (without naming them) but didn't explain the parallax method that
underpins the whole thing.

He's usually better. Maybe the dumber downers have got to him.

--
Max Demian
  #34  
Old August 23rd 19, 08:29 PM posted to uk.tech.digital-tv
John Hall[_2_]
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Posts: 338
Default Nothing worth bothering about on tv

In message , tim...
writes
"The basic telescope was invented due to a *revolution* in science"


I don't remember anyone saying that. (But my memory is rubbish
nowadays.) Wasn't the argument more that the telescope CAUSED a
revolution in science, which seems fair enough.
--
John Hall
"If you haven't got anything nice to say about anybody, come
sit next to me."
Alice Roosevelt Longworth (1884-1980)
 




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