Orwell Astronomical Society (Ipswich)
Renovation of Orwell Park Observatory, 1972-2009
The period from the foundation of OASI to the late-1990s were times of major renovation at Orwell Park Observatory. Members of the Society devoted much time and energy to restoring the observatory, which had deteriorated badly in the time since its construction, and in developing new facilities. Records (limited in extent) exist of the work from 1972 onwards. This article summarises the main highlights.
In early 1972, the shutter of the equatorial dome malfunctioned. The Committee of OASI worried that any further attempt to open the shutter could result in it becoming jammed open, or worse still falling off (!), so declared the refractor out of action. George Sargeant, Vernon Wilkes, David Bearcroft and others effected a repair and, by March 1972, the refractor was in operation again. Unfortunately, the repair was short-lived and, by May 1972, once more the shutter was broken and the telescope out of operation. This situation necessitated the rescheduling of OASI's first Open Day, originally scheduled for May 1972, to September of the year.
An appeal for volunteers to come forward to assist with redecorating the observatory was posted in the March 1972 Newsletter (edition number 2). It was the first of many to appear over the years!
A plasterer was engaged and, on 22 July, worked in the observatory. Subsequently, on 10 and 12 August, decorating parties comprising members of OASI were at work.
The observatory was closed May-July 1973 for essential maintenance. An electrician was employed to rewire the observatory and fit new sockets, a new supply meter and new lights on the stairs, equatorial dome, transit room and club room. Members of OASI repaired the roof of the transit room and began repairs to a broken doorway. The object glass of the Tomline Refractor was removed and sent to Horace Dall of Luton for cleaning and re-figuring.
The most noteworthy event in 1976 was the installation by Alan Smith of noticeboards around the central pillar at the level of the belvedere. The size of the noticeboards meant that they had to be hoisted up the outside of the building by rope. Figures 1 and 2 show the operation in progress.
Some decorating was undertaken during the summer months of 1977 prior to the Open Day on 24 September. As usual, members were encouraged to volunteer for decorating parties by notices in the Newsletter.
Also during the summer, one of the wheels at the top of the observatory tower, upon which the dome rests, was adjusted to bear its fair share of the weight of the structure. This improved the ease with which the dome could be rotated.
The original RA drive for the Tomline refractor was a magnificent piece of Victorian clockwork engineering powered by the descent of two large weights down the hollow shell of the observatory tower. The use of two weights enabled continuous operation, the observer re-winding one weight while the other powered the mechanism. Speed control was achieved by means of a centrifugal governor. The output of the mechanism was coupled via a drive-shaft to a worm wheel which engaged with a large toothed, RA drive wheel at the base of the polar axis. The drive wheel had 1440 teeth and the nominal rate of rotation of the worm wheel was therefore one RPM (there are 1440 minutes in a day). See figures 3 and 4.
Unfortunately, the drive mechanism had suffered through neglect and vandalism over the years. By the time OASI took up residence in the Observatory, it was still functional, but was not reliable and required much maintenance and ongoing "tinkering". The general consensus was that even if OASI completely re-conditioned the drive, it would not achieve accuracy better than ±10% of sidereal rate. Options to replace the centrifugal governor with a modern servo-based system utilising strain gauges were considered but rejected as impractical and a decision was made to construct an electric drive system.
The torque required to drive the telescope was 0.025 Nm. OASI had minimized this figure by adding an additional counterweight to ensure that the entire structure to be driven (telescope plus associated mounting superstructure) was well balanced. It was hoped that this would reduce wear on the drive gear train.
Several considerations went into the design of the drive system:
Following due consideration, in early 1978, Alan Smith and colleagues constructed a mains-operated electric drive based on a variable frequency oscillator and squirrel-cage motor. The motor was coupled via a flexible shaft and an original set of bevel gears to the worm wheel meshing with the main RA drive wheel. The torque transmitted to the RA drive wheel was much in excess of the requried 0.025 Nm. To optimise efficiency, the telescope balance was optimised as part of the work. A cover was to be fitted to the drive and gear-train for safety reasons. In use, the drive was generally rested after running non-stop for up to an hour, in case of overheating (although in practice, this did not appear to be an issue).
Testing on solar and stellar observations, running the drive for up to an hour, indicated that it ran slightly too fast, but within 2.5% of sidereal time. This was adequate for visual observations, but less than ideal for long-duration photography. Completion of the drive created renewed interest among members of the Society in using the telescope.
Other major items of work were also undertaken during the year. Throughout the summer, the decorating parties did their customary work and, from late summer until November, a professional electrician engaged by Orwell Park School completely rewired the observatory tower, replacing all fittings, conduit and cable.
The new electric drive fitted to the refractor in 1978 made the instrument much more usable. However, room for improvement remained as follows. The worm wheel could be disengaged from the RA drive wheel in order to allow free movement in RA for initial positioning of the telescope. Unfortunately, the 1440 teeth of the RA drive wheel did not give enough resolution when re-engaging the drive, and could cause "jogging" of the image, enough to move a carefully-centred object out of the field of view at high magnification. The solution was to fit a limited-torque friction clutch, enabling adjustment of the telescope in RA without disengaging the worm wheel; this had the secondary benefit of protecting the teeth of the RA drive wheel from being stripped if there were any accidental sudden movement of the instrument. In fact, the original drive had included just such a clutch mechanism, controlled from the eyepiece end of the telescope by a sequence of mechanical linkages. Unfortunately, this had suffered theft and vandalism over the years, as a result of which it no longer functioned and insufficiently much remained to enable it to be reconstructed with certainty. Martin Cook and David Payne therefore fabricated a new clutch mechanism which was installed in early 1979 (see figure 5). Unlike the original, it had to be operated from the base of the polar axis, rather than the eyepiece end of the telescope.
Further, in installing the new drive mechanism, it had been noticed that the telescope was not well-balanced. Members of OASI therefore fabricated and installed a new, adjustable counterwight system for the telescope, to ensure that it functioned well with the new RA drive mechanism.
Unfortunately, during 1979, a snow-like fungus infested the space between the two elements of the object glass, reducing the limiting magnitude of the instrument by some 3-4. The object glass was therefore once more returned to Horace Dall of Luton for cleaning. The Committee of OASI hoped that the increased publicity around the telescope at this time would encourage additional members of OASI to to use it regulary. Unfortunately, this ambition was only partially fulfilled.
Another area that benefitted from significant repair and refurbishment during the year was the Orwell Park clock tower. Tomline had commissioned Adam Thomson of New Bond Street, London to build the clock in 1859. It benefits from a quarter-hour chime and an hourly chime sequence played on 16 bells. It is mounted in a square tower some 15 m high, driving four faces. At the top of the tower is a small viewing platform from which, no doubt, Tomline and his guests enjoyed the view over his estates. Unfortunately, many birds had nested in the tower and the associated twigs and other detritus had jammed the clock mechanism, preventing it from functioning. (Fortunately, the bells of the chime remained in good condition.) Starting in April 1979, Martin Cook and David Barnard spent many evenings and weekends working to renovate the mechanism and finally, in September of the year, their efforts were successful, the clock running to within one second a day, the quarter-hour chime functioning and the hourly chiming mechanism only awaiting the provision of new steel springs before it could be brought back to life. Figures 6-9 show the tower and the clock mechanism itself. (The wires running vertically upwards from the mechanism in figure 7 are to actuate strikers on the 16 bells producing the hourly chime.)
1981 was a year of major repairs and reconstruction, with almost continuous activity from June until the end of the year. Numerous articles in the Newsletter called for volunteers to join work-parties. The observatory was closed for several months, during which time it resembled a building site rather then a place of astronomy. The biggest single job was to sand down and re-varnish the mahogany panelling lining the inside of the dome. This was an arduous task which took many weeks of sustained hard work on top of tower scaffolding. Peter Parish deserves particular mention for his powers of stamina which enabled him to continue sanding, atop the tower scaffolding, apparently tireless, for hours on end. After the sanding, we applied gallons of polyurethane varnish to the mahogany panels. This was probably the first time that the lining had been re-varnished since the observatory was built.
Meanwhile, outside the observatory tower, suspended on a mountaineer's climbing harness, Colin Button played Spiderman while others supplied cement so that he could re-point the observatory tower, repairing over a century's worth of damage caused by frost and weather. The East Anglian Daily Times featured his activities on the front page. Although Colin was the only person brave (foolhardy?) enough to wear the harness, David Barnard took to stretching down from the roof of the transit room to re-point the brickwork on the walls of the transit room. David also carried out repairs to the roof of the transit room in order to make it waterproof.
The next area of work concerned the door to the lift shaft. Some time after building the observatory, Tomline had installed a hydraulic lift to all floors. Over the years, the lift had ceased to function and had become derelict with dry rot infesting the flooring and door surround. The door led to a 20 metre drop down the lift shaft to the basement and, for obvious safety reasons, had been firmly sealed shut with many long nails. We removed the door and its rotten frame and, with the benefit of the facilities of the Orwell Park School woodwork room, constructed and fitted a new frame and reshaped and re-hung the door. (Note that both door and frame are curved in order to fit with the circular profile of the wall of the dome.) The new door was locked with a key, rather than nails, enabling easier access for the construction of a floor across the lift shaft some years later. (See figures 10-13.)
We reconstructed the interior walls of the equatorial room. This necessitated removal of loose brickwork and plaster and the laborious transport of large quantities of sand, cement, plaster and water up the 111 steps to the room before reconstruction could begin.
Besides repairing the inside of the equatorial room, we mounted a major effort to reconstruct the base of the dome shutter. The bolts holding the bottom shutter track to support brackets had been scraping lead from the roof when the dome was rotated (in fact this had been one of the major causes of damp in the observatory). We had to raise the support brackets before we could repair the lead. It was while attempting this task that disaster struck. Three cast iron brackets supported the shutter track. One had been removed for repositioning the track; unfortunately this caused the load on the remaining two to be too great, and both fractured, leaving the shutter inoperable. Fortunately, Martin Cook, with assistance from Anglia Grain Installation Ltd of Wickham Market, was able to fabricate two new steel support brackets and effected a repair, positioning the new brackets so that they did not scrape the lead roof. (See figures 14-16.)
Following the reconstruction and renovation work, we undertook some painting. We painted the equatorial room and transit room and also sanded down and re-varnished the floor (it soaked up four coats of polyurethane varnish before we achieved an acceptable finish!) We gave the telescope another coat of battleship grey paint. We fitted rubber-tyred wheels to the observing chair so that it would not damage the polyurethane varnish on the floor of the dome.
Finally in 1981, we installed a new electric RA drive for the telescope (see figure 17). It was based on a stepper motor coupled to a gearbox, from which a drive shaft protruded, at the end of which was the worm wheel meshed with the RA drive wheel. This arrangement superseded the drive installed in 1978 and reduced the extent of the drive train required to transmit torque to the RA drive wheel. It also had the advantage that the rate of the stepper motor could be adjusted, enabling sidereal rate to be set exactly. The new drive was commissioned on 18-19 October 1981, once decorating had been completed in the Dome; it ran until it was replaced on 09 September 2009.
After all the hard work in 1981, we had a well-deserved rest in 1982 and undertook little work of note. The School employed decorators to paint the external windows of the Observatory and renew two window frames.
In June of 1982 we noticed that a number of dead bees began to accumulate on the floor of the dome.
Our biggest job in 1983 was to repair the roofs above the stairwell, lift shaft and transit room. We also fitted a pair of new wheels to the bottom of the dome shutter, which greatly improved the ease of opening and closing. The gutter around the base of the dome had almost rusted away, so we applied several coats of resin to the gutter walls. We also painted the notice boards surrounding the circular column in the belvedere.
By the summer of 1983 it became apparent that we had a major infestation of bees! Throughout the summer there was a constant accumulation of dead and dying bees in the observatory. Every week, we swept them up, numbering many hundreds at a time. Eventually, we discovered a bees nest inside the top of the shutter - it was estimated that in mid-1983 there could have been some 60,000 bees in the nest, increasing at about half that number annually. By late 1983 we made preparations to evict the bees.
Martin Cook, Colin Button, Dave Barnard, Eric Sims and Alan Smith gathered, on 02 January 1984, accompanied by a local beekeeper, Mr Drew, to evict the bees. Our strategy was to effect removal of the nest and bees intact, and not to destroy any of the bees unless absolutely necessary. A member of the party informed us that bees were not active beneath 64°F so that attempting the job in early January would be quite safe - that was our first big mistake!
Operations began at 10.00am. The first job was to manhandle a 10 m ladder up the 20 m side of the observatory tower (the spiral stairs were not designed to admit such a long object) and into the dome together with circular saw, hammers, crow-bars etc. Next, we persuaded Colin Button (of Spiderman fame two years earlier) to ascend the ladder. Using a circular saw, Colin very carefully cut and removed a mahogany plank lining the dome shutter. We found that Colin had scored a bull's eye and, on removal of the plank, we could see the edge of the honeycomb. He then removed several more of the mahogany planks to reveal more of the honeycomb. By this time, some of the more inquisitive members of the nest were flying around investigating the cause of the commotion - so much for the theory of inactivity due to the cold!
At this point, with the bees becoming increasingly active, it became apparent that we needed a more stable platform from which to work. We assembled a scaffolding tower (borrowed from Orwell Park School) and Mr Drew took over removing the mahogany planking from the rather apprehensive Colin. Eventually, the whole honeycomb was visible, in the shape of a central core with several tongues of honeycomb extending from it. Together with the honeycomb was a football-sized huddle of 25,000 - 40,000 bees, by this time, extremely agitated! We made a strategic withdrawal for a couple of hours, in the hope that the bees would quieten down.
Returning to the bees some two hours later, we found that they had indeed quietened down. Mr Drew brought a large box equipped with special frames on which to tie the honeycomb. He cut surplus honeycomb from the edge of the nest and dropped it into the box in order to provide food for the bees over the winter. He then cut each of the 50-60 cm long tongues of the honeycomb away from the copper clad outer skin of the dome and tied them onto the specially constructed frames in his box to act as a new home for the bees over the winter. Once all the honeycomb had been transferred, it only remained to sweep up the few thousand remaining bees clustered inside the shutter and drop them into the box, and to replace the mahogany planking inside the dome. Later in the spring, the bees would be re-housed again into a traditional hive: Mr Drew explained that, as the queen bee was unharmed, the colony stood a good chance of survival.
Alan Smith documented the episode in the February 1984 issue of the OASI Newsletter under the title Search for the Beehive1. Figures 18-23 below illustrate the operation.
Other work in 1984 included completing the bench seating in the clubroom, replacing two floorboards in the dome and painting the dome walls again.
In 1984, we also upgraded the Tomline Refractor by fitting it with a guide telescope to assist with long exposure photography.
In 1985 we replaced another floorboard in the dome and then devoted most of our efforts to the Tomline Refractor. We removed the periscopes (used to enable an observer at the eyepiece to see the declination scale) and re-aluminised their mirrors. We constructed a camera bracket and lubricated the telescope’s declination and RA axes.
In June 1986, we removed the OG of the Tomline Refractor from its cell and cleaned it.
Later in the summer the year, a major structural failure occurred. Orwell Park School had arranged to have the flat roofs of the transit room, lift shaft and stair well re-leaded (the work was originally scheduled for September 1985, but was delayed). Workmen winched the rolls of lead up the lift shaft and left them in a heap in the middle of the dome floor - we were very lucky that it did not collapse under the weight! When the workmen lifted the lead rolls to the outside of the dome, they rested them on the dome shutter step and, unfortunately, the cast iron structural ring at the base of the dome fractured under the weight. We therefore constructed and fitted new shutter support brackets and bolted a 3 m x 75 mm steel strengthening ring onto the inside of the dome track under the shutter step. (We secured it using approximately 50 bolts.) The Dome was out of operation during July and August while the repairs were undertaken.
Work in 1987 started in a small way with the fitting of a new lock to the door of the equatorial room. From this, however, our efforts rapidly grew into major repairs and painting in order to get the observatory in a good state for the 21st anniversary celebrations of OASI the following year.
We completely refurbished the transit room. The first task was to remove the shutters (which close the observing slot), replace rotten timbers in them, and rehang them. Next, we took up the old floor and replaced it with a new one. Research into the construction of the observatory conducted shortly before the work began had revealed that the original floor of the transit room had been lower than the one taken up, so we reinstated the floor at the original level and installed a new set of stairs down to it, whereupon it became immediately obvious that the transit telescope was more accessible in use, especially for stars at high altitude. We recast the tops of the pillars of the telescope mount. The final activities in the transit room were painting the walls and staining and varnishing the floor.
In the equatorial room, some of the mechanics of the dome were in need of repair. We constructed a new shaft for the dome rotation wheel and repaired two of the wheel boxes, raising one on refitting by 5 mm so that it helped to support the weight of the dome. We stripped all paint from the walls then hired a professional plasterer one Saturday to plaster the walls: he was able to complete in a morning an area that would have taken us many weeks! We strengthened the supports under the floor of the room, then painted the walls and woodwork, sanded the floor then stained and varnished it.
Having completed renovation of the transit room and dome, we began work on a part of the observatory that had not been decorated since its construction: the spiral stairwell leading up to the dome. It had always been difficult to keep the spiral staircase free of dust, and painting all the surfaces would help to alleviate this problem. We decided to use Sandtex on the walls and concrete paint on the treads. The walls were very porous and required two coats of Sandtex, so painting continued beyond the usual summer maintenance period, right through into 1988.
On the night of 15-16 October 1987, a violent hurricane swept across England causing much damage and many casualties. Although the storm damaged many trees in the vicinity of the observatory (see figure 24), the building itself remained intact and required no special maintenance, a testament to the quality of its construction.
Decorating work continued through the winter months of 1987-88, the first time that it was not suspended over winter to enable observing. We finally finished painting the spiral staircase by the end of April 1988. Fortunately, all our efforts paid off as the dust level was indeed greatly reduced.
We then began work on another area of the observatory that which had not been tackled before, namely the clubroom. We painted the floor and applied Sandtex to the stone areas of the walls.
Orwell Park School, under the normal maintenance scheme, replaced two windows in the Observatory Tower that had been in very poor state for as long as anyone could remember (one of the windows, situated in the stair well, had been missing a pain of glass for at least ten years). Two of the balcony doors were also missing pains of glass, and had been boarded up with sheets of plywood for many years; again, the School replaced the glass.
During 1988 we also undertook additional work in the transit room. Opening and closing the roof shutter had always been a precarious operation: it involved climbing onto the roof and manipulating the shutter by hand. Originally the shutter had been opened and closed from the inside via a rack and pinion mechanism. The original mechanism still existed (at least in part) but the method of use was a mystery. We assumed that some form of counterweight system must have been in use but had gone missing. We designed a new counterweight system and OASI member Martin Cook fabricated it. The new system for operating the transit shutter worked well (with a little care!) and was much safer than the old one.
In the equatorial room, we undertook some work including: renovating, varnishing and re-carpeting the observing steps, refurbishing the periscopes used to view the declination circle on the refractor, cleaning the clock drive and painting the telescope. However, we declined a request from an anonymous member of OASI to remove all paint from the telescope and polish the brass of the tube to its original glory.
We started 1989 by re-pointing the brickwork in the clubroom. At the end of March, we began a major project to floor over the lift shaft at the level of the clubroom and again at the level of the equatorial room, creating two new rooms. We dismantled and removed the remnants of the lift mechanism, with the exception of the winding wheel and vertical lift tracks which were too firmly embedded in the fabric of the building. We then fitted RSJs, mounted joists and finally fitted floorboards. We completed the job in 1990. When completed, we used the room at clubroom level to house the library and for general storage while the room at dome level became a map room and storage area for eyepieces and other observing paraphernalia.
In 1996 we undertook much painting of the external woodwork of the windows on the Belvedere.
After several years with little significant effort devoted to maintenance and renovations, we once again erected tower scaffolding inside Orwell Park Observatory dome! Once the scaffolding was in place, the first job was to grease the top shutter rail. The shutter had been getting harder to open during the last year or so and, following greasing, it opened and closed more easily and smoothly.
The second job was much more involved, and had been pending for a considerable time! The observatory dome rests on a cast iron ring, which in turn rides on top of several cast iron wheels mounted in the walls of the observatory tower, enabling the dome to be rotated. In 1986, while repairing the roof of the transit room, workmen had rested rolls of lead on the step of the dome shutter and the weight had caused the dome ring to fracture. We had repaired the ring with a 3 m long curved steel strip bolted to it internally and a new bracket fixing the superstructure of the dome to the ring. However, since that time, the cast iron ring had developed several hairline cracks. We were faced with a situation whereby if the problem continued to worsen, the dome would no longer be safe to rotate and the observatory would be put permanently out of action.
We first investigated the inner construction of the dome to assess the extent of the problem. We carefully removed two of the mahogany boards cladding the inside of the dome. Except at the bottom of the dome, immediately above the ring, the internal materials were quite sound. However, brackets holding the framework of the dome to the ring had corroded through ingress of damp and the passage of time. We decided to tackle the problem by extending around the entire circumference of the dome the steel strengthening ring fitted to the cast iron ring under the shutter step in 1986.
On Wednesday 06 August 1997, Martin Cook delivered two lengths of curved steel strips, each about five meters long, to the Observatory (figures 25-26). Members of OASI had to manoeuvre the strips round the Observatory stair-well up to the belvedere. From there, we moved the strips onto a balcony and then hoisted them up the outside of the tower on to the roof of the stair well, before lowering them through the dome shutter on to the floor of the dome. After delivery of the steel strips, work continued apace on Wednesday 13 August. On that evening, amid a great volume of noise, we began the task of fixing the first bar to the ring. At the peak of activity during the evening, there were four people drilling holes, one tapping a thread, and one inserting a bolt in every completed hole. Work continued for several successive Wednesday evenings, until the new strengthening strips were securely fitted and painted and the considerable mess made during the fitting was cleaned up!
In summer 1999 we once more painted the walls of the stairwell to the equatorial dome. This was a major job, and many members of OASI assisted with the work.
In the disused lift shaft in the early 1990s we had created a new floor at the level of the Belvedere. The floor was supported by a steel framework that was secured firmly to the walls of the shaft. Unfortunately, the steel frame raised the floor level above the floor level of the Belvedere, providing a nasty step on the threshold of the room. We used the new space to house the library bookcase (a large glass and wood case). The move of the bookcase from its former site in the Belvedere had been a big success, removing a major obstruction which prevented efficient circulation of people whenever the Observatory was busy. However, the new space proved to be less than ideal as a library: it was dusty and poorly lit and the large step on the threshold resulted in many members almost cartwheeling out of the library! We therefore began a major project to renovate the lift shaft:
Our original plan was to complete the work within two - three months, then move on to repainting the Observatory. However, the first task was to remove the floor and steel frame supporting it and this turned out to be an elongated process due to the difficulties of working safely in the lift shaft, requiring use of an industrial safety harness. By early summer 2002, it was apparent that our estimate of timescales was utterly unrealistic: although the library had by then been re-floored, work was still in hand to strip and re-line the internal walls. Hopes remained high that the work would shortly be completed and repainting could begin, but this too turned out to be a triumph of optimism over reality. By summer 2003, we had made good progress and were re-fitting the internal walls, complete with damp-proof lining. We finally completed work in time for a ceremony to open the new library on 15 May 2004.
Figures 11-13 (above) illustrate the lift shaft in 1980, before any modifications were made. Figure 27 (below), taken in mid-2001 as renovation work was about to begin, looks up the lift shaft showing from underneath the steel-framed floor that OASI had installed in the early 1990s. Figures 28-42 show subsequent aspects of the renovation work during 2001-04. Photographs provided by James Appleton, Martin Cook, Roy Gooding and Ken Goward.
For several years prior to 2009, the electric RA drive motor for the Tomline Refractor had been unreliable. (The drive had been installed in 1981 - see above. The problem was traced ultimately to a hairline crack in the motor drive board.) In early 2009, the handle of the RA clutch broke and this catalysed an overhaul of the entire drive mechanism. Martin Cook and James Appleton fitted a new handle to the RA clutch and fabricated a new electric RA drive. The new drive benefitted from a more powerful stepper motor, all-digital operation and adjustment of RA drive speed via an FM handheld controller rather than a cable-linked unit, the cable of which had often proved to be a trip-hazard in the dark of the dome. Figure 43 shows the new drive mechanism with its cover open.
The Beehive Cluster or M44 is a star cluster in the constellation Cancer. It is just visible to the naked eye on a clear, dark night.
Roy Gooding, David Payne, Ken Goward, FRAS & James Appleton