Three small telescopes: Dollond, Dixey, and A. N. Other

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These three telescopes are all small and easy to carry – they could be described as “Pocket telescopes” but you would need a deep pocket, since they are all around 6” long when folded up. All with three draws, they are the shortest units that can perform reasonably well, without going as far as having a multi-draw construction, a design that gets heavier and larger in diameter in the pocket. All three of these are the same sort of length when extended, 17 to 19 inches.

The interesting part is that these three illustrate several different aspects of design, and span around 120 years in terms of date of manufacture.

  1. The Dixey scope

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So named because it is engraved “C.W. Dixey, Optician to the Queen, New Bond Street, London” on the first draw. Charles Wastell Dixey worked there (at number 3) from 1839-1862 – so the Queen was certainly Victoria – and prior to working on his own he was in partnership with his Uncle George, and supplied George IV and William IV too. Those telescopes were labelled G & C Dixey.

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This scope is of a classic design, with two lens cartridges at either end of the first draw, each with two lenses in the Schyrle-Huygens eyepiece arrangement, which is the format generally adopted for telescopes after 1800. An interesting feature of this design is that the sliders mounting each draw are sized very close, making a good seal on the outside of the smaller tube. So Dixey added air release holes in each draw, to allow the air to escape as the scope is compressed. Because they are a good fit, he did not need to cut the full flap in the slider (that can be tightened using hand pressure) to enable later adjustment, that featured in many earlier designs. However he did make two parallel cuts in the slider on each side, creating a ‘double ended flap’ that can still be squeezed to tighten a little, if needed.

The different feature here is that the scope is all brass in construction, possibly reducing the maximum OD of the unit, compared to a mahogany barrel – it is about 1.25” OD round the Barrel, but 1.375” where the brass raised around the objective area. The outside of the barrel, instead of being leather covered, which became the normal covering later, is brass, with the surface scratched in a fairly irregular pattern, then coloured in a brown shade, to simulate the appearance of wood.

The objective is a dual element lens, in an achromatic combination, held in place using a threaded ring on the inner side. It would appear that originally there was a brass protective cover fitted over the objective, this seems to have been lost. The eyepiece has a captive sliding cover in the screwed on cap. This cap holds the first lens cartridge in place, which is a push fit into the first draw.

Accession Number 238

  1. The Dollond scope

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This Dollond is engraved ‘Dollond London x15’, all in capitals with the angular, heart shaped “O” letters. This dates it to after WW2, maybe in the 1950s. So it is 100 years further on than the Dixey: but still the same style of lens construction. The view through has the same sort of magnification, but the image is much bigger, and appears to give a wider field of view.

This could be down to the larger diameter lenses used in the eyepiece section: the three draws are altogether larger diameter and feel much stronger than those in the Dixey. The barrel of the Dollond is also larger by a little, measuring 1.625” OD. The largest, third draw is 1.375”, compared to the Dixey at 1”.

Where the Dollond scores comes later: it just feels right in the hands and is easy to use. This one has the brass barrel covered in pseudo leather – which is probably real….

Accession number 45 (a long time ago!)

  1. The Other One

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There are no markings engraved on this scope. It appears to be a standard three draw, small scope from the 1800 -1850 period, but is in remarkably good condition. This is maybe because of the substantial felt lined leather case that came with it.

It is a little unusual in that it has a brass barrel, rather than a wooden one, and this is coated with a veneer or similar covering. The surface of this veneer is textured, or roughened, to a sort of matt finish. It also has a sun shade over the objective, a third the length of the barrel, with a side sliding cover assembly over the lens that can be unscrewed. If the scope is used with this lens cover in place, but with the slider open, the diameter of the window opening onto the objective lens is only about 0.75”. The eyepiece cap screws into the top of the first draw, but this has an integral long parallel section, 11mm long, that prevents the first draw pushing further into the barrel.

The Schyrle lens system

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The three lenses in the Schyrle eyepiece design. The two lenses pictured still in the cartridges are there because their threads are too tight and difficult to remove. Both cartridges pictured have external threads on the bottom, to attach to the adjacent brass fittings.

It is inside the scope that the real differences become obvious. This was a real surprise, after the outside looked like a conventional early 1800s design. First the objective is a single lens, not an achromatic doublet. Then there are only three lenses in the first draw, making up the eyepiece assembly. These are equi-spaced, by about 6cms, and the lens closest to the eyepiece cap is in fact at the far end of a 3cms long cartridge, maintaining this large distance between the observing eye and the first lens. Plus there is a ‘Field Stop’ orifice close to this lens, on the objective side. This is a different eyepiece lens system to normal, it is a Schyrle lens system. This was supposed to have not been used after about 1750, since the achromatic objective lens and the Schyrle-Huygens eyepiece then took over. The Schyrle eyepiece was popular from the late 1600s to mid 1700s, and was developed by Anton Maria Schyrleus de Rheita, a Capuchin monk in 1645.

Others, notably Chris Lord, have suggested that Schyrle three lens systems were used on telescopes well into the early part of the C19th: the construction of this scope does seem to bear that out, in that it would appear to be of the style of the early 1800s. The internal connectors between draws are conventional, but close fitting brass to brass, such that there are no cut-outs that can be pressed down to tighten the connections up.

A characteristic of the Schyrle system is that the positioning of the eye along the optic axis is fairly critical, and equally any misalignment of the lenses in the cartridges – for example by cross-threading – makes it difficult to locate the image (ie sometimes it is difficult to use the scope without just seeing a grey blurr!).

The OD of the sunshade on this scope is 1.375”, and the barrel is 1.25”. The third draw is 1” diameter, like the Dixey. But as mentioned above, the window on the objective restricts its open diameter to 0.75”, whereas the Dixey objective lens visible OD is 1.125”, so gathering more light.

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Accession number 211

Conclusion

Three scopes, all very similar in performance, but all with their different features. All are compatible with the Ramsden small scopes from 1790, and the Andy McNab scope from the C20th. It really comes down to which ones are easiest to use and carry!

The Schyrle eyepiece system used in the third model is very unusual. It was seen once before in a James Chapman octagonal telescope in my collection, but this one really did date from the late 1700s. The scope described above looks to be a much later design, and in my opinion dates from the early part of the 1800s, maybe as late as 1840. A similar design of telescope, but one which uses the Schyrle-Huygens eyepiece system with 4 lenses in the first draw, and dates from around 1850, is the John Hewitson unit described earlier.

Hewitson scope (centre)

The Hewitson scope is the smaller, second one down: this photograph shows my first three significant purchases, back in 1992

 

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