The Bolton Group

In its prime, 1890

The historic Stonyhurst Refractor, its sale and subsequent re-purchase is a complicated story. The telescope dates from the 1890s, the mount from the 1860s, when Stonyhurst was a premier observatory. However, after many years of use it was neglected and slowly sank into dereliction after the Second World War. It was sold but was never restored by its new owner who eventually offered it for sale. Fortunately it was re-purchased by Stonyhurst College and returned to its rightful home. It has been reassembled almost single-handedly by Fintan O’Reilly in its original observatory, which had fortunately survived. However to return it to working condition Fintan needed help and called us in.

You get some idea of how big it is from this!

Greasing the maim polar axis

Gerald fitting the new motor drive.
Note the original clockwork drive lower right.

The telescope is big and several parts were either broken or lost. We carried out a quick investigation in April 1999. The first problem was to lubricate the main polar axis which we managed to do on our first visit by disassembling the top two RA bearings. The bottom one which takes the thrust could only be tackled if the tlescope was dismantled. On a subsequent visit we used the telescope to get a better understanding of the problems. The views of the Moon were brilliant with a steady image that only a refractor can deliver. There was quite a bit of violet fringing but nothing to worry about. The telescope is only f/12 so is not fully corrected but for its intended use as a visual telescope this is not an issue.

The Problems

The problems we identified were:-

1. A simple motorised drive was essential. The original falling weights type drive was not functioning with transfer gears missing. Our conclusion was to leave it in tact and not prejudice future restoration but bypass it with an electric drive. We had a 30 rpm 12 volt DC heavy duty motor, which with a new 1:120 worm gear in addition to the main 359 tooth wormwheel, would provide the right tracking rate.

2. The telescope was also originally equipped with manual slow motions. The RA one used its own worm gear but appeared to have been rebuilt out of alignment so restoring it without rebuilding the telescope would be difficult.

3. The DEC slow-motion had a few missing components but probably could be rebuilt but would be left to later.

4. The telescope was out of appreciable balance. Removing one weight was too much so an intermediate weight was required. We would need to fabricate a new boss to add a more suitable one.

5. The focuser assembly had obviously been used to manually move the telescope and over the years had become worn, loose and broken. Providing handles for moving the telescope would stop the problem returning but rebuilding the focuser was also required.

6. The DEC clutch appeared to have either worn away or needed adjustment. However, no means of adjusting it could be found.

To sort (2) and (6) we would have to dismantle the 3 ton telescope! That would be a major undertaking and take at least a full weekend.