Friends of Wandsworth Common — Heritage Talk
The world's largest refracting telescope, Wandsworth Common, 1852
Tonight we are going to be talking about one of the more enigmatic features of Wandsworth Common, and our speaker Greg Smyth is very well qualified to tell us about it. He has created an extraordinary online museum — the Craig Telescope Museum — which is remarkably comprehensive; if you want to know anything about the Craig telescope, that website will tell you. Greg has worked at the Royal Observatory, Greenwich, for twenty-one years, where he presents planetarium shows to schools and the public, and supplies diagrams and celestial maps to Astronomy Now magazine. We are in extremely good hands. Greg, over to you.
My involvement with the Craig telescope began with a trip I organised in 2003 for the Orpington Astronomical Society, of which I am now president. It was a tour of London's old historic astronomical sites — or, as my wife calls it, places that aren't there any more, which is actually a rather good description. London is almost uniquely well suited to a tour like this, because during the Renaissance and the Industrial Revolution, when the British Empire was at its height and everything was growing and being understood, it was a period of astonishing scientific bloom. The tour takes in James South's observatory in Kensington (the building and garden are still there, now called Observatory Gardens), William Huggins's observatory in Tulse Hill (the building is long gone, replaced by blocks of flats), and various other sites.
When we arrived at Wandsworth Common — the site of the world's largest telescope in 1852 — and I saw the little area still marked on the map as “The Scope,” I thought: I have to investigate this further.
Let me briefly explain how a proper telescope works. It is mounted on an axis aligned with the Earth's rotation — pointing at the Pole Star — so that it simply undoes the rotation of the Earth. You set the declination (the up-down angle) to find your target, then let a motor drive the telescope slowly around, tracking the object as it moves across the sky. Elegant, precise, and repeatable: you find Saturn one night, and you can find it again the next.
The Craig telescope did not work like this. It was, from an astronomical engineering point of view, thoroughly bad. Instead of a polar axis, it was mounted altazimuth-style — that is, it moved up-and-down and left-and-right independently, with no coupling to the Earth's rotation. The tube, 80 feet long and weighing 220 tons, hung on a chain inside a brick tower 64 feet tall. Moving it to a target and then keeping that target in the eyepiece as the Earth turned was a constant battle. But we will come back to exactly how rubbish it was.
The Craig telescope was the brainchild of the Reverend John Craig, vicar of All Saints Church, Leamington Spa. He was a remarkable and exasperating man in equal measure.
He was born just outside Dublin, into a clerical family — his father Robert was also a reverend. John Craig became an evangelical vicar, very much the raising-of-hands and raising-of-voices variety, and he was by all accounts a magnificent orator (though probably with a slight lisp, if you study the jawline and lips in his portrait). He was also obstinate, argumentative, and utterly single-minded. He loved debate and always wanted to win.
A flavour of his character: when the competition was held to design the new All Saints Church in Leamington, Craig organised it — and then entered it himself. He won. Unfortunately he understood nothing about structural engineering, which is why, if you drive past All Saints today, the spire is on the side of the church: the roof was simply not strong enough to support it in the intended position. His parishioners loved him; the council and the authorities found him nearly impossible to deal with.
He also claimed to have invented the phrase “one foot in the grave.” He developed circulatory problems leading to gangrene in one foot, which had to be amputated, and announced from the pulpit: “I already have one foot in the grave.”
Craig's first wife, Anne Alie, married him in 1831 and bore him a son. She died of cancer at Hastings in 1834, though rumour had it she had been killed by a bullet fired at Craig by a group of men who took exception to his vigorous denunciations of the Pope — he had been pursued through the streets one night and shots were fired, but he escaped unharmed. By Christmas of 1834 he had married his second wife, Helena Johnson, who brought with her a fortune of £56,000 — equivalent today to approximately £9.3 million. Craig, it must be said, saw his opportunity. The telescope, even in 1852 terms, would cost the equivalent of about £1.5 million today. That is essentially what he took from her to build it.
To understand how Craig came to build on Wandsworth Common, you need to know that he had previously been vicar at Fetcham in Surrey, and engineered a preferential exchange with the vicar of Leamington — the two men simply swapping parishes. Critics accused him of being motivated by the greater income from the Leamington glebe lands; his defenders insisted it was purely a desire for a wider scope for his ministry.
Having settled in Leamington, Craig needed land near London on which to build his telescope. He could not build inside London itself because he simply could not obtain a suitable site; the atmospheric pollution was a secondary concern. He approached William Wilson — the founder of Price's Patent Candle Company, a lessee and resident of Wandsworth Common — who communicated Craig's interest to Henry Goodford, manager of the Fourth Earl Spencer's estate. A letter dated 10 February 1852 from Wilson to Goodford records:
I have had a visit this morning from Mr Craig, Vicar of Leamington, to request the assistance of the lessees of the Common in procuring for him the grant of a small portion — say about an acre and a half — of the Common for the erection of a telescope of great power. I have assured him that he may depend on receiving every facility to further his views from the lessees, and have given all the instructions in my power.
The land was granted at no cost, but with the condition that if the telescope fell into disuse the site would revert to the Fourth Earl Spencer. That condition would matter.
The man selected to design and build the telescope was William Gravatt, a brilliant civil engineer who had worked on the Thames Tunnel under Marc Isambard Brunel. On one occasion, when the tunnel flooded at night, Gravatt simply dived into the dark water and saved men's lives. He was, by any measure, a remarkably brave and capable man. His knowledge of telescopes, however, was essentially nil, and Craig's forceful personality appears to have overwhelmed his better engineering judgement at every turn.
A portrait obtained from the Institution of Engineers — a daguerreotype which Greg photographed and enhanced — shows Gravatt looking perfectly confident and competent. His will, when he died, left an extraordinary collection of swords and daggers to his nephew, having never married and had no children. Make of that what you will.
The telescope tube was 80 feet long and hung on a chain inside a brick tower 64 feet tall, the whole structure weighing 220 tons. The lens, 24 inches (about 61 cm) in aperture, was ground by Thomas Slater — not very well, as it turned out. At its lowest magnification the telescope gave 125×, meaning the full moon would appear about the size of a dinner plate. Saturn at the eyepiece was moving visibly, crossing the field of view at a quite brisk pace.
The mounting was altazimuth: a “dolly” running on a circular rail at the base of the tower allowed the lower end of the tube to be moved left and right; a chain-and-winch system raised or lowered the tube within the dolly. The design bore an uncomfortable resemblance to the telescopes of the seventeenth-century astronomers Hevelius and Bayer — all rigging and sheets like a sailing ship, with no means of locking on to a target and tracking it. Once you had found something, you had to keep finding it again from scratch.
Gravatt's partial remedy was ingenious: he fitted a micrometer screw to the eyepiece end, turned by a winch handle. When the Moon was on the meridian — transiting directly south — it is moving almost purely east-to-west, so cranking the handle provided something close to equatorial tracking in the one direction that mattered. It was reported that Gravatt could keep the crater Aristarchus continuously in the cross-wire by humming a tune to regulate the steady turning of the handle. Meanwhile, a photographer named Prout, who had a studio in Bond Street, attempted to take photographs of the Moon using the wet collodion process, which required an exposure of 35 seconds. At 125× magnification, a 35-second exposure of a fast-moving object produced, inevitably, a smear. Prout was also observed counting the seconds too loudly, disturbing the man at the handle. It was not going to work.
Despite everything, some observations were made. The most notable was the purported observation of the “crepe ring” of Saturn — a faint, dusky inner ring whose existence had been debated. The Illustrated London News of 16 October 1852 reported:
The Northumberland Achromatic at our Cambridge University was brought to bear by Professor Challis on the rings of Saturn; and also with the giant reflector of the Earl of Rosse. Hence it became a matter of intense interest as to whether there was in reality a third ring. We are happy now to exhibit an engraving of the ring as seen in this country in the Craig telescope.
Whether the Craig telescope genuinely resolved the crepe ring, or whether what was seen was an artefact of its flawed optics, remains uncertain.
The only drawing made from observations at the eyepiece of the Craig telescope survives. It is not impressive.
By 1854 the telescope had fallen into disuse. Dismantling began in 1856, though the structure stood until about 1870, when it was finally removed. The bricks were recycled — as was standard Victorian practice, no brick being discarded if it could be reused. Greg eventually tracked them down.
At the junction of Trinity Road, on the corner, stands a building that was originally a hotel and is now a restaurant. If you look carefully at the first floor, you will see a curved parapet of a very distinctive brick colour. When the hotel was being built, the builders saw the Craig telescope tower being demolished across the Common, went over with their carts, collected the bricks, and used them. The tower of the Craig telescope is incorporated into that building. Greg's wife visited and held one of the original bricks next to a photograph of the tower: an exact match.
Having established the approximate location of the telescope from historical maps — the Stanford map shows a black blob labelled “Observatory” very clearly — Greg obtained permission from Wandsworth Council to conduct an archaeological dig on Wandsworth Common as part of Channel 4's Time Team open-dig weekend in June 2003.
Preparation included a ground-penetrating radar survey, arranged at short notice through a company called Sandfords. Greg telephoned, explained what he needed, and mentioned in passing that he needed it done the next day and could not pay for it. There was a long silence. The managing director called back twenty minutes later and said, essentially, that they would do it anyway. Two young men arrived the following morning with a large piece of equipment and dragged it noisily over the brambles and tree roots of the Common. The results were returned on Friday; the dig was on Saturday.
The dig team — Greg, his brother Paul, a friend with a metal detector, and two children from a neighbouring family — were allocated three holes, each one metre by one metre by a third of a metre deep (they ended up digging three, which strictly exceeded their allocation; Greg asks that this not be widely publicised). An archaeologist from the Time Team was assigned to supervise them and confirmed they were proceeding correctly before moving on to other sites. The Bramley and Orpington Archaeological Society also conducted a resistivity survey.
The radar survey did not show the telescope foundations clearly — the terrain was too uneven — but it did pick up a circular anomaly consistent with the outer rail on which the dolly ran. The dig itself produced fragments of brick, mortar, render, roof tiles and a few nuts and bolts consistent with the telescope structure. Nothing else of significance was found: nothing had ever been built on that patch of Common except the telescope, and nothing has been built there since.
The final discovery came just as the team were packing up on the Sunday. Greg was looking down the little path through the trees when he realised that all the activity over two days — the people, the tea trays, the moving about — had flattened the brambles. And there, clearly visible, was a circular depression in the ground: the exact footprint of the tower. They had not needed to dig at all.
On 6 January 2004, some seven months after the dig, Greg received an email from a resident on Wandsworth Common called Bridget Bishop, who said she thought she might have a photograph of the telescope. He drove over immediately. She produced a thick album; inside was a photograph about the size of a postage stamp, taken by Geoffrey Bevington, the well-known local photographer. Despite its small size, it contains a remarkable amount of information: the telescope is clearly no longer in use — there is rust staining, the dolly wheels are lying flat, the lens has been removed and a wooden cap fitted to the end of the tube. A two-storey cottage stands nearby; a large counterweight box is visible. Bevington had used a camera with a tilting back plate to correct the perspective distortion caused by looking up at a tall structure.
A second photograph was subsequently found online — owned by a dealer who would not sell it but agreed that the digital image could be used freely. This shows the telescope from a different angle, with the workhouse of St James's visible in the distance. In this image the dolly and its running mechanism are clearly visible: a rail on which the dolly moves in and out as the tube changes angle, and a small A-frame winch used to raise or lower the chain. The azimuth wheel — the large ring on which the dolly rotates — is also clearly seen.
The telescope was not the end of Craig's adventures. In 1870, after the telescope was dismantled, he built an ice-skating rink — not the first in Britain, but, inevitably for anything Craig touched, not a commercial success either. He was briefly imprisoned on suspicion of financial irregularities — the Council had found what appeared to be irregularities in the accounts — but the charges were not proven and he was released. The day he was released, he gave a sermon. He died in 1876.
Was there a spiral staircase inside the tower? We don't know for certain, but the tower was not very large in diameter, and we think it was probably more like a mill: vertical ladders through holes in the successive floors, with one going up from one side to roughly the middle of the next floor, and another continuing from there. You would have somebody at the top receiving instructions shouted from below — something like: “Go round a bit more.” That is essentially how we think it worked.
Why is a passionate astronomer interested in a telescope that didn't work? Because of the intrigue of it all. You had serious engineers — the workshops near the London docks fabricating the steelwork, the River Wandle being used to haul heavy components on barges up to Wandsworth, William Gravatt who had saved men's lives in the Thames Tunnel — all involved in this extraordinary and ultimately futile enterprise. And you had this peculiar, brilliant, impossible vicar at the centre of it. After the telescope was dismantled he built an ice rink, was thrown in prison, came out and immediately gave a sermon, and died the following year having lost a very great deal of other people's money. It is just intrigue, layer upon layer of it.
Did the dig find anything other than telescope-related material? Nothing at all. The ground-penetrating radar, the resistivity survey, the metal-detecting and the digging all confirmed the same thing: nothing has ever been built on that patch of the Common apart from the telescope, and nothing has been built there since. Whether it will remain undeveloped is another matter — there is a constant pressure to build, and I won't pretend I am entirely opposed to housing in principle, but that particular spot has a strong claim on its history.
Was there a plan to use the telescope's mounting system more ingeniously? The altazimuth mount — altitude and azimuth, up-and-down and left-and-right — is fine for hunting comets, where you are sweeping the sky rather than tracking a specific object. For anything requiring steady, prolonged observation, it is very poor. There is no evidence that Craig or Gravatt considered a proper equatorial mount (with the axis aligned to the Pole Star to undo the Earth's rotation), which is what any astronomer of the day would have recommended. George Airy, the Astronomer Royal, wanted nothing to do with the project, and there is almost no correspondence between the Craig telescope and the Royal Observatory at all. I think the subject was simply too embarrassing to acknowledge.
What was Craig's design based on? That is the puzzle. The original sketch — probably drawn at one of Craig's meetings, possibly by Henry Goodford, Lord Spencer's manager — shows a design by someone who clearly knew nothing about how telescopes work. There is a staircase at the back for no apparent reason; there is no means of moving the telescope to a target. It does not look as though Craig studied other large telescopes of the period and decided to copy them. He seems simply to have had a vision and instructed people to realise it.
What happened to Helena Johnson, Craig's second wife, whose money funded the telescope? We know very little about her emotional response to any of this. Craig's son Robert, whom Helena had warmly embraced as her own, died aged twenty-one, which was a profound sadness. The £56,000 was largely consumed by the telescope and Craig's subsequent ventures. One imagines she was not delighted, but the record is silent on the subject.
Why did Craig go to jail? There were alleged financial irregularities — it was suggested he had diverted funds in connection with the competition to design All Saints Church. The charges were not proven, however, and he was released. Whether he had actually done it in a sufficiently disguised way to avoid prosecution, or whether he was genuinely innocent, we cannot say. What we know is that he walked out of jail and gave a sermon the same day, which suggests a remarkable degree of self-possession.
Was the telescope near Wandsworth ever confused with the Earl of Rosse's telescope? There is an estate agent's brochure from 1911 for Burntwood Lodge — a house on the edge of Wandsworth Common — which claims, in passing, that the telescope just along the road was the Rosse telescope before it went to Ireland. This is entirely untrue and shows how myths propagate. The Buckingham telescope, which I showed briefly, had its lens sent to Calton Hill Observatory in Edinburgh, where we believe the 21-inch lens is still held today.
Greg, that was an absolute tour de force — spellbinding, and I've learned more this time than the first time I heard you speak about it. Thank you very much indeed. Greg will now make his way back to Tunbridge Wells.