This telescope is a product from a major telescope maker from the 1790s. So, bought on Ebay, it came looking sad and unloved, held together with masking tape. But with everything in place, more or less: maybe not in the right places however.
Taking it to pieces, the first draw, the eyepiece, did not work as an inverting microscope, which is always a bad sign. Then the view through the unit was rather how I imagine tunnel vision to be, a view down a long narrow tube. No real field of view available.
The name Ramsden
However, the telescope is a Ramsden, made maybe 1790, engraved properly (on the left side, as was the standard in 1790), and is complete with the objective lens cap. The objective lens is clean and complete, the barrel in good condition. Inside, the lenses in the first draw looked a lot the worse for interference, one stuck in the threads, and with gripper marks round one of the brass lens mounts as evidence of a lot of previous stress. It also appeared that they had been shuffled, so did not work well optically. Indeed the first draw worked as a microscope only when reversed. Then one lens was found to be jammed into the cartridge with an unusually positioned aperture assembly pressed inside the cartridge.
On removing this aperture, an unsupported unmounted lens is found: it is the necessary to start to sort them out. In this scope unusually the threads all seem to be much the same size, for the lens mounts, so that makes it easier to get them mixed up. Later the manufacturers “keyed” the lens threads to make things easily located. It transpired, after hours of trying, that this bare lens must have been a substitute for a broken one, and it was just not right. The lenses and cartridges, with their integral apertures, were returned to what seems to be the correct orientation and position by comparing the design with three other Ramsden scopes in the collection. I then realised that this one is almost identical to #51, a Ramsden bought many years ago, and reported on this website already. That report, and others, also gives the history of Ramsden in the 1790s.
Eventually the lens was replaced by a slightly smaller lens and mount from a J Webb similar scope (#263), and the whole thing fell into operation properly. There were two ‘John Webb’ instrument makers reported by Gloria Clifton, one from 1792, and his son from 1800-1847. This telescope was labelled 408 Oxford Street, which is where Clifton says the son was based – for a short period – in 1808. Telescope #263 has other separate problems, such as a broken objective lens, so a temporary loan of this number 2 lens to the Ramsden is not a restriction. However the search continues for a suitable leens and holder that might fit the Ramsden thread, as the J Webb lens is small and only wedged in position.
The brass polished up well, with Brasso. The main barrel is mahogany, and the old French polish scraped off easily to reveal the wood, which has a couple of longitudinal cracks, but nothing serious. This is scheduled for repolishing. The objective holder has one small screw missing, which needs to be replaced. The objective lens end-cap is present, and in good condition. As yet the eyepiece sliding lens cover is still stuck firmly in the open position.
The pictures that follow show images before the renovation, as it was received.
Then these pics are after polishing, but before any French polish added on the barrel.
In the last picture the second lens cartridge from the bottom of the first draw can be seen: the lens facing the eye is the one that has been attacked with some form of plier grip. Also on the right, the slider on the first draw is seen, where the thread is adjacent to the knurled shoulder. Better made telescopes a few years later would have had the threaded section at the opposite end of the slider.
The telescope has ended up a fairly well made, neat and effective telescope, with really good optics, as you would expect from Ramsden.
Owners and applications?
We do not know any of this. This smaller size unit (7.5″ compacted, and 22″ extended) could have been used by a cavalry officer, or on board a sailing ship, or indeed just by a country house owner. It has not been bashed about, and appears undamaged apart from the one broken internal lens, which has had to be replaced. Overall diameter is about 1.8″ at the largest part over the objective.
Equally we have no knowledge of the ownership of the scope even recently. The Ebay seller lived in Barnard Castle in County Durham: a lot of sailors came from the northeast – Capt Cook came from Middlesbrough after all.