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Impressions of Hardraw, November 09 - 11, 2007 ...
No clear skies, but a 16" truss-tube reflector to play with
...
Many years ago, while studying for “HNC with endorsements” (1)
in Applied Physics at John Dollie’s (2), there was a somewhat eccentric
Optics lecturer by the name of Bill Michaels who delighted in the perverse.
Of his many gems, such as whether Galileo was more famous for inventing
the telescope - which he didn’t, or having a large but unconfirmed
number of illegitimate children - which he reputedly did, I particularly
recall the matter of ‘collimation’ - which should never have
been allowed to happen at all.
Etymological studies reveal that the Latin word ‘collimare’, had
it existed, must have come either from : ‘lima’ - a file, ‘limare’ – to
file, and therefore ‘collimare’ - to file together. This would obviously
commemorate the work of a dedicated team whose combined physical efforts were
needed to adjust the shape of the telescope in order to make the thing line up
at all. or alternatively from : ‘limare’ – to fling mud, therefore ‘co(n)llimare’ – to
fling mud against. This, of course, is an action readily understood by anyone
who has tried to line up the optics of a large and wayward instrument like our
16 inch Dobsonian.
However, the words ‘collimare’, or ‘collimatus’, the
act of doing it, were never actually uttered in the streets of Rome at all. The
words were, in fact, ‘collineare’ and ‘collineatus’,
meaning, quite clearly, to line up together. One or other of these correct words
appeared in a document by Cicero who lived between 106 and 43 BC. Now Marcus
Tullius Cicero was a statesman, lawyer, political theorist, philosopher, orator
and writer of prose, so exactly what it was that he was trying to line up, and
how it fitted in to his various duties, remains a mystery. As far as we know
it had nothing to do with Astronomy.
Whatever the reason, this particular document was referenced at the start of
the 17th century when the telescope had been invented and somebody, having wrestled
with the problem of making all the bits point in the same direction, wanted to
tell his friends what he had been up to. Since the language of choice to impress
people in those days was Latin, where else to look for a suitable word but in
the great classical writings of many centuries previously.
Unfortunately the person who went to the trouble of tracking down the required
word, managed to misread it (3), confusing ‘ne’ with ‘m’,
and the new word was born. Once coined, all the other telescope aligners of the
time, including Johannes Kepler in 1604, were happy to use this word since it
sounded quite trendy and, anyway, nobody else could be bothered to plough through
all that Latin translation to check it (4).
‘Collimation’ it was and ‘collimation’ it has been ever
since.
1) I always wondered whether, if I achieved my three endorsements, I would have
my HNC repealed.
2) John Dalton’s College of Technology, subsequently Manchester Polytechnic,
subsequently Manchester Metropolitan University, subsequently ... Who knows ?
3) Whether this was due to bad handwriting, cheap spectacles or poor photocopying
of the original document is not recorded.
4) This duality is, of course, particularly relevant for those aligning telescopes
constructed with tubes made from either aluminium or aluminum, other victims
of a reading or writing error.
Malcolm Beesley
Dobsonian fun at Hardraw
The society has had a 16 inch Dobsonian
for some time. The scope was built around someone’s mirror. It was displayed
at the B2B conference recently. It has been in need of some attention for some
time and has always proved hard to collimate. According to Malc, there is no
such thing word as collimation, it was a misreading of the word co-lineation.
This was according to Bill Michaels of John Dalton’s College of Technology.
This fact has been etched in to Malc’s brain (please see previous article).
We (the five technical astronomers) systematically went through every possible
adjustment. The MaccAstro brains had to tackle the following problems:
We did
not know if the focal length of the mirror matched the length of the light tube.
In the end we decided it did.
We had to sort out the position of the primary
mirror – with
a spanner. A paper reinforcement ring was used to make the centre of the primary
mirror.
We then had to alter the length of the struts in the open tube by jacking
up some of the nuts at the ends of the tubes. We will lock the nuts with Zeneith’s
shimmering aubergine nail varnish when we dismantle it. This enabled us to align
the secondary mirror with the primary. We needed two lasers (one cost £3.99
from Morrison’s garage) to achieve this.
Testing it out was a problem.
It had to be put on a flimsy picnic table as it was cloudy so no overhead viewing
was possible. The best object was a cairn on Pike hill. The scope was pointed
almost horizontally and had to be raised to look above the stone walls.
We are
hoping to restore the telescope into working order in the future. We will need
to work out the focal length and take advice as to whether to replace the mirror
or to recoat it.
Stephen Willcox
Click on an image to see a larger version.
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 July and August updates ...
The bright twilight nights are slowly giving way to darker skies and the prospect of revealing a little-known nightly sight. Away from the towns and cities, the Milky Way will soon be glimpsed meandering through the constellation of Cygnus. This river of stars was worshipped by the ancient Egyptians ... Nowadays, especially when we approach the end of Summer, it's astronomers that turn their gaze skyward and praise the sight of a myriad of stars arching high above them.
The following sections have been updated: This month's night sky and observations.
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Would you like to join our newly formed visual observing group? We will now be holding regular observing sessions at some of our dark-sky sites across Macclesfield. If you would llike to be added to our contact list, don't delay ... Click
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For information on our observing
field trips to Hardraw, Yorkshire ... Click
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Our Workshops continue to be a
great success. As a result we are looking for more of you
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members. Let us know if you'd like to get involved ... Click
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