Renovating an old relic:
A Watson Royal microscope.

by Hugh Clayton, UK


 
   Some years ago, I spent a lot of time tinkering with old optical instruments and vowed never to buy anything without first looking at it face-to-face. Then the Internet came along, and for some sentimental reason I couldn't resist the sad-looking relic, described as a 'Watson monocular', that was posted last year on the website of an auction house.

   There it sat incongruously in a furniture sale, next to a couple of brass telescopes. But the auction house was 250 miles from home and I had no chance of visiting it before the sale. I took a deep breath, entered a bid across the web and won the 'monocular'.

   It arrived several fraught weeks later via the impenetrable jungle of a Parcelforce warehouse. The good news was that, although two of the control knobs had fallen off in transit, nothing was missing from the stand itself and nothing that had survived was broken. The only visible identification marks were the Watson name and address and the serial number 11509.

   The case and the containers for the objectives were all missing. The condition of the stand was poor, hinting at decades of neglect punctuated by moments of abuse. The coarse, fine, substage and stage adjustments were all jammed solid, the mirror was badly tarnished and the top lens of the condenser was heavily pitted. The condition of the coarse and substage adjustments suggested that somebody had tried to wrench them round after they had become stuck.

   Restorers and users of old microscopes will be familiar with the two greens. A dark green residue is left by the heavy garage grease that some owners plaster onto the moving parts of their instruments. If it's left for long enough, it sticks moving surfaces so firmly that they seem to have fused together.

   Light green streaks on the outer tubes, stage and knobs suggest that somebody found the lacquer peeling off and decided to do something about it. The streaks are left by a household metal polish that sweeps the lacquer remnants away and leaves the bare metal prone to tarnishing and decay.

   Stand 11509 had green all over it, and was clearly going to need a complete strip-down. But first, what was it? The Watson name and the serial number stamped on the back were reassuring: the company's stands were always solidly made and able to stand abuse, and the earlier ones are straightforward to dismantle. Those protruding control knobs, all ideally placed to be bent or snapped off by hurried users, can be a boon to the restorer. The serial number suggests a date around 1910. Plenty of information about the company's instruments is available on the Web and in CD-ROM and photocopied reprints of original catalogues and handbooks.

   Before the First World War, Watson and many other manufacturers offered an enormous variety of stands, but did not mark them with the model names. But I am convinced that this one is a basic 'Royal'. It lacks the circuit stage and extra-large build of the van Heurck series, but is much heavier than the cheaper Edinburgh Student's type.

   The reinforced limb, the broad 'soup spoon' mirror attached to the back of it and the lumbering racked drawtube all shout 'Royal'. Construction could hardly be simpler. The stand is made from only four materials: brass (mostly lacquered), iron, steel and cork (inserted in each of the three feet to keep the stand steady). It arrived with a long low-power eyepiece marked with a 1, an anonymous Watson condenser and three badly tarnished objectives in a heavy nosepiece. They were a Zeiss B and D and a Leitz 1/16.

   I suspect, but can do no more, that the objectives were sold with the stand. Their appearance fits the date suggested by the stand's number, and by that time Continental manufacturers were making big inroads into the British market.

   Watson's 1905 catalogue shows just how far they had penetrated. A bare Royal stand with the built-in mechanical stage but without lenses or case cost £14 and 10 shillings. For £15 (an extra 2.9%) Watson would also sell you a less tough mid-range Leitz stand with a plain stage and cheap substage. But for that price you acquired it in a complete outfit of stand, three eyepieces, three objectives, a respectable condenser and a case. So somebody paid a lot of money for 11509 and whatever accessories came with it, and it seemed a pity to leave it as a lump of useless jammed metal and clouded glass.

The stripdown and reassembly were slow, but not difficult. I applied penetrating oil to the stuck parts and stored the stand for several days. I use another brand in preference to the usual WD40. It seems to work better without causing damage, as long as it doesn't reach the lenses. I learned the hard way many years ago that the oil can take its time to penetrate. The fine adjustment on 11509, part of which is hidden inside the limb (See My First Proper Microscope by Paul James, Micscape April 2000), took 10 days to move.

   The next task was to take the whole stand apart, labelling everything and marking the position of each spindle on its rack, ideally with blobs of different colours for different fittings. Racking adjustments which aren't correctly reassembled may move stiffly even after cleaning and lubricating.

   Labelling is essential. The design may be straightforward, but stand 11509 is made from almost 80 parts held together by more than 40 screws. The screws on these old microscopes need special care: they are usually made of lacquered brass with deep slots with vertical slides. A modern screwdriver with a tapered blade can cause damage, and a knife with a snub-end blade is often better.

   Reassembly started with polishing all the moving surfaces with that household metal polish, which will not harm an unlacquered brass surface. Lubrication is an area of lively debate: Watson used to recommend clock oil, while various specialist greases are available for modern microscopes, often only in far greater quantities than any amateur would want. I use small amounts of a well-known brand of bicycle oil which seems to have the right consistency. It is easy to overdo the lubrication, and parts that don't want to move smoothly probably won't be persuaded to do so by being bathed in lubricant.

  One great help with Watson stands - and one of which the company was enormously proud - is the use of compensating slits on the moving parts. The idea was to tighten the slits with the screws provided to compensate for wear in normal use. But the slits can also be loosened, and this feature can ease jammed slides apart and help the penetrating oil.

   One of the fascinating aspects of dismantling a museum piece like 11509 is that you usually learn something about the development of the microscope and the success or failure of manufacturers to improve their products. It seems incredible that this stand - essentially a tough 19th century relic with 20th century fittings - was made in the lifetimes of people who are with us today.

   I have never met a Watson fine adjustment that was not solid and true, and this one is no exception. But the coarse adjustment is only just up to the job of holding the heavy drawtube when the nosepiece and three objectives are fitted.

   A small addition to the weight is the eyepiece adaptor which enabled users to swap from the old-style capped 'English' eyepieces to the narrower 'continental' type which, even in 1910, were fast becoming the worldwide standard. The substage fitting is made to the 'continental' standard which persists today.

   All this means that solid early 20th century stands make unshakeable platforms for modern as well as old lenses. There's still plenty of work to do on 11509, notably cleaning the objectives and condenser. But it has already had a little outing with a slide. A beam of light managed to bounce off the clapped-out mirror and punch its way through the ravaged condenser to the grubby low-power objective. The result was a surprisingly bright and detailed 'narrowfield' view of part of a fly's head.

All comments to the author Comments to the author sent via our contacts page quoting page url plus : ('hclayton','')">Hugh Clayton are welcomed.

Acknowledgement: The author thanks his son Geoffrey Clayton for taking the digital photographs.
 
 

Images.
Click on each image to view larger ones (ca. 150 kbytes each).


The dismantled stand: brass and more brass.
The heavy and complex tube assembly with eyepiece adaptor on the right.
The main parts of the mechanical stage.
 

 

The optics (from left): Zeiss D, Leitz 1/16 and Zeiss B objectives, eyepiece and Watson condenser.
The stand reassembled: an unshakeable platform for lenses ancient and modern.
The stand height when inclined as in the photo is 35 cm. 
 

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