WADHURST ASTRONOMICAL SOCIETY

APRIL NEWSLETTER 2005

INDEX: MEETINGS, OTHER NEWS, CONTACTS

MEETINGS

MARCH  MEETING

MARCH MEETING

The Craig Telescope at Wandsworth

Talk by Greg Smye-Rumsby on Wednesday 16th March 2005.

      Greg Smye-Rumsby gave a very amusing and animated presentation using excellent computer graphics, telling of a long forgotten leviathan of a telescope built in the mid 19th Century.

      For quite some time, Greg had collected data and built up a dossier of information on long since vanished observatories and telescopes and when he recently came across a reference to a telescope tower built on Wandsworth Common that had finally been removed in 1877, he remembered the name and became sufficiently interested to research any information he could from archives and references in the local library.  Very little was known of tower or of the telescope itself.  He did discover that the telescope had been built by the Reverend John Craig and began by finding out all he could about this apparently very persuasive and overbearing cleric, born in Ireland in 1805.

      The Reverend Craig presided over the rebuilding of All Saints Church, although owing to his convincing manner left out the tower, which had to be added some years later.  Craig's other interest was astronomy and he acquired a 24-inch lens for an astronomical telescope.  At the time this was the largest lens in the world.

      Greg discovered that Craig had approached the Fourth Earl Spencer who owned Wandsworth Common and managed to obtain the use of part of the Common for 1 (52 by today's standards), but for a limited period of 14 years. After complaining that this was not long enough in astronomical observatory terms, it was agreed that the land could be used in perpetuity until it could no longer be used for the purpose of observing.

       After some initial research, Greg discovered a drawing made by Beard Engineering but there were too many inconsistencies for it to half worked.  But it did reveal that the engineer for the telescope and the tower was William Cravat.  Then a much more precise sketch by a man called Sargent revealed that there had been a round tower with a rotating cap on top from which a chain hung down with a large metal loop through which the 85 feet long mild steel telescope tube could be supported and raised up and down.  The eyepiece end of the telescope was mounted on a dolly that could be moved round the tower on a track.  The drawing also showed a large due cap and a small flap towards the top of the tube, which it is thought could be opened to allow hot air inside the tube to escape.

      There were two grill-covered windows at the top of the tower, through which Greg believes operators would have been able to communicate with people on the ground when aligning the telescope.

      On a track running round the base of the tower was box at the bottom of the chain, and after some thought by Greg's brother proposed that this box was in fact a bogey into which the chain would be stored as the telescope was raised and lowered.

       It has been calculated that the maximum angle the telescope could have been raised to would have been 74 degrees and the minimum must have been 4 degrees.

      One alarming fact was that it was thought that the tower itself had no foundations as such!

      Greg was delighted when he was approached by the television "Time Team" programme who wanted to perform a scientific archaeological dig and he had no hesitation in suggesting the site of the Craig Telescope.

      The precise location was unknown and they had to approach Wandsworth Council and National Heritage for permission to carry out the dig.  After researching old maps of about 1862 an observatory was found in the grounds of what had been Burntwood House in the southwest corner of the Common.   Then on the more precise Whitbread Map of 1871 a "Telescope" was marked inside the junction of Routh Road and Lyford Road.

      Permission was granted and Greg was asked where a test trench should be dig.  The land had never been built on before or since and Ground Penetrating Radar was requested which revealed a certain amount of compaction but since there had been no foundations all they found was one brick from the tower, a roof tile and one sheered off nut.  The rest of the land must have been pretty well cleared after being dismantling in 1877.

      Probably as a result of the programme, Greg was shown the only photograph of the tower and telescope taken by Geoffrey Bevington in 1852, confirming the accuracy of Sargent's drawing, and also showing buildings in the background that finally showed the most precise position of the tower.

      The focal length of the 24-inch lens was 23164.8 mm with a focal ratio of 38.  Slung beneath the main tube was a 6-inch finder with a focal length of 1524 mm, focal ratio 10, and known eyepieces for the 3-ton telescope where between 125 mm and 750 mm. 

      The outer track for the eyepiece dolly had a radius of 52 feet, but evidence for this was not discovered until a recent return visit by Greg when he discovered some remains across an overgrown footpath they had all been using throughout the dig.

      Whatever happened to the main lens?  Greg suggested it could now be a rather nice coffee table somewhere!

THE APRIL MEETING

      The next Society meeting is on Wednesday 20th April 2005 when the speaker will be John Murrel talking about "Virtual Observatories - fireside astronomy".

      The meeting takes place as usual in the Drama Studio at Uplands College, Wadhurst, and commences at 7.30 pm.

FOLLOWING MEETINGS

      Ian Reeves has been very busy since taking on the post of Society Secretary and has already completed the programme of speakers for the rest of this year.  Advance announcement of these talks is as follows:

      Wednesday 18th May 2005.  The speaker will be Alan Smith from Horsham whose talk is called "Deep Sky for all Seasons"

      Wednesday 15th June 2005.  Dr. Andrew Coates from the Mullard Space Science Laboratory gives a talk called "The Cassini - Hygens Mission".

     Wednesday 20th July 2005.  Konrad Malin-Smith will be guiding us around "Pulsars".

     There will be no meeting in August.

      Wednesday 21st September 2005.  Alan Drummond will be giving a talk entitled "Perception in Astronomy".

      Wednesday 19th October 2005.  Peter Parish introduces us to "Planets and Small Telescopes".

      Wednesday 16th November 2005.  Gilbert Satterthwaite talks about Sir George Airy and nineteenth century instruments in his talk called "Positional Astronomy".

      Wednesday 14th December 2005.  PLEASE NOTE THAT THIS MEETING HAS BEEN BROUGHT FORWARD A WEEK!  (Instead of the third Wednesday, this will be the second Wednesday in the month)  On this occasion the speaker will be Norman Walker talking about "Getting the Measure of the Stars).

COMMITTEE MEETING

      There is to be a meeting of the whole Committee at 8.00 pm on Monday 11th April 2005 at the Abergavenny Arms in Frant, just two miles south of Tunbridge Wells on the A267 road.  If any members of the Committee wish to raise any particular points, could they let the Secretary, Ian Reeves, know before hand if possible.

      Any non-committee member of the Society is also very welcome to come along.

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OTHER NEWS

OUR NEW TREASURER AND SUBSCRIPTIONS

      At the close of the 16th March 2005 meeting a fresh Bank Mandate was duly completed to formally include Michael (Mike) Wyles, (elected to the Committee on the 15th December 2004) as our new Treasurer.

      A few Society members have not yet renewed their membership for the current session, which began in November.  Mike would be delighted to accept a cheque for 15 for a single member or 20 for joint membership either sent to him or at the next meeting.  Cheques should be made payable to Wadhurst Astronomical Society.

      Mike's address is 31 Rowan Tree Road, Tunbridge Wells, Kent TN2 5PZ.

THE NIGHT SKY IN APRIL

      Spring has arrived and with it an extra hour of daylight!  This means that the night-sky is also an hour later as well, courtesy of the Government.

      We have just about lost the winter constellations now and the spring constellations are appearing.  Leo has become dominant to the south with the group of stars making up the lion's head looking rather like a reversed question mark, Regulus acting as the full-stop underneath.  Regulus is a relatively hot star at a distance of about 77 light years away and so has an apparent magnitude of 1.36 although its absolute magnitude us -0.52. (Absolute magnitude is worked out as if the star was 10 parsecs away)  If Regulus was at the centre of our solar system it would be 130 times brighter than our sun.

      About 40 degrees to the west is Procyon in the constellation of Canis Minor, a star looking very much as our Sun would look at that distance.  Procyon is 11 light years away.

      Midway between Regulus and Procyon is a circular group of fainter stars.  This is the head of the constellation of Hydra, the water snake and is the longest constellation in the entire sky since the tip of its tail is 70 degrees away to the south.

      Corvus the crow can be recognised by the four bright stars fairly low down in the southeastern sky forming the shape of a kite.

      For those interested in deep sky objects, M104 is just six degrees above the eastern-most of these bright stars is called the Sombrero Galaxy.  Although it has an integrated magnitude of 8.3 it can be just made out with a pair of binoculars as a fuzzy shape.  With a medium telescope, the shape of the sombrero can just be made out, but with a CCD the line of dark matter orbiting the galaxy becomes quite spectacular.  The integrated magnitude is the magnitude of a group of stars as if they were to be contracted down to one point, so can be quite disappointing when compared to a true star of the same magnitude.

      Jupiter is just another eight degrees to the northeast and is now an important part of the Southern sky and is always worth observing with any telescope or binoculars.  The four Galilean moons are Io which orbits closest, then Europa, Ganymede and Callisto and all can easily be seen unless passing in front of or behind the planet.  Even then it is sometimes possible to see the moon passing above the planet with its shadow visible on the surface below.

      The moon is full on the 24th of April when illumination from the sun shows up Tycho's rays most clearly.  Tycho is the deep 85 kilometre diameter crater towards the south (In the lower part of the disk when viewed through binoculars.  Upper part when viewed through an inverting astronomical telescope).

      Many of the moons features are best seen when the light of the sun is low on the lunar horizon.  For instance the spectacular Apennine mountains  on the southern side of the Mare Imbrium, the large "sea" towards the north of the moon's face is ideally seen on the 16th April.  This range is about 700 kilometres long.

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CONTACTS

Chairman          Tim Bance                   01732 832745      timbance@hotmail.com

Secretary         Ian Reeves                        01892 784255

Treasurer         Mike Wyles                   01892 542863   mikewyles@globalnet.co.uk

Publicity & Web site           Michael Harte       01892 78329      michael@greenman.demon.co.uk

Editor            Geoff Rathbone                01959 524727       Geoff@rathbone007.fsnet.co.uk

Any material for inclusion in the May Newsletter should be with the Editor by April 28th  2005

 

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