John Bell

When I was a teenager I was keen to get into telescope making. I was a member of the Newcastle upon Tyne Astronomical Society and had avidly read “The Glass Giant of Palomar” by Woodbury. Funnily enough I didn’t aspire to be Porter, Anderson, McCauley or Hale. I was bitten by the “21 men in white” – the team of guys who would slosh rouge onto the 200" polishing lap for months on end-and that’s what I did.

Newcastle Astronomical Society was very much linked to Grubb-Parsons in those days. Grubb Parsons was a part of C A Parsons – the company founded by Sir Charles Algernon Parsons. C A Parsons were world leaders in producing turbine generators for power stations. His pride and joy was the record breaking turbine powered boat the Turbinia. (this is on display in the Newcastle Science Museum). Parsons was always interested in astronomy and telescopes ( his father was the Earl of Rosse who built and used the 72" telescope at Birr Castle in Ireland) and joined up with Howard Grubb, the son of Thomas Grubb, to form the new optical company Sir Howard Grubb, Parsons & Co Ltd.

Grubb Parsons made many large telescopes over the years – a series of 72" scopes on cross-axis mounts were made for Australia, South-Africa, Canada, Egypt and France. The world’s largest refractor - 41" for an observatory in the Crimea was almost completed, but WW1 and the Russian Revolution intervened. The mount was completed but rumour has it that it was in the Tyneside docks for many years, waiting for the customer to pay the bills! I don’t know its ultimate fate. The optics were reworked later into a large meniscus lens, and was used as part of the autocollimating setup for later, larger telescopes. I have a copy of a sketch of the 41" telescope in the works. David Sinden rescued this drawing and many other treasures from a skip when the optical works was being wound-up.

Optics for some of the world’s great scopes were made at Grubb Parsons. The 98" Isaac Newton Telescope and a new slightly larger mirror before the move to La Palma. The UK Infrared telescope mirror was completed to a much higher wavefront profile than the IR band required. It will work very well in the visual band. The AAT and the UK Schmidt (and I think a new achromatic Schmidt plate for the Oschin schmidt at Palomar), The William Herschel Telescope was the last great telescope produced at Newcastle.

When I started as an apprentice in the optical works in 1965 the managing director was George Sissons and the works manager was George E Manville – a real gentleman of the old school. The optical division was run by David S Brown. David was for many years the secretary of the Newcastle Astronomical society and was a stalwart of the BAAVSS. David oversaw the optical design, testing and manufacture. I remember polishing a Schmidt corrector for a camera of his own design. It was about 8" aperture and had two correcting plates. His right hand man in the optical shop (it was termed the glass shop) was David Sinden. David Sinden was a true optical genius a good boss and a very good friend. Here are a few snippets of the many memories I have of David during the years of 1965-70 when I was there:- The first job David gave me was to produce some toroidal mirrors. These had different radii across different diameters and were probably for something like the GP infrared milk analyser. This was quite a big deal for a 17 year old and I always appreciated being given such an interesting start to working life. There were routine jobs in the shop and interesting ones. You would sometimes spend a few hours chamfering mirrors – that is standing at a rotating cup style turntable and pushing the mirror or lens blank in some coarse carbo to chamfer the edge so that it didn’t break off tiny shards of glass to scratch and ruin the work. Some of the small spectrometer mirrors were rectangular so of course they were cut in a diamond saw – rather slow and tedious work. Even the task of putting the curve on telescope mirrors – not rough grinding but diamond tool curve generating wasn’t really very exciting but was of course necessary. At lunch times some of the men in the shop would eat and play cards. I would usually wander into David Sinden’s office for a chat. He was always ready to talk astronomy, optics, photography philosophy or indeed anything. He was a bit deaf and often had bad earache but never showed any sign of bad temper.

His office had a desk, chairs, bookcase- crammed with astronomy and optics and a plan-chest full of interesting stuff. On the bookcase was a full size working model of Newton’s original reflector, a wooden model of the perfect foucault test doughnut and a wooden cone accurately cut to show all the conic sections- circle, ellipse, parabola and hyperbola. There were always a couple of Grubb’s lightweight metal mirrors as paperweights or whatever.

David would often open the plan chest and bring out either his astronomical photographs, usually taken with aero lenses on quarter plate. I remember some nice pictures of Comet Arend-Roland from 1957. Also pictures of telescopes made in his amateur days before moving from Billingham in Teesside to Newcastle. There were also photos and spectra of meteors. He, with Harold Ridley were BAA pioneers in meteor spectrography using whole plates and 12" F2.5 Aero-Ektar lens and an objective prism.

His favourite scope was a 12" f8 which was kept outside protected by a tarpaulin. He was proud of the resolution this telescope gave despite the murky and often turbulent North East atmosphere. David also had a 6" Dall-Kirkham folding telescope with an erecting lens (to help eliminate unwanted skylight in the wide open tube telescope). Another scope was a 9" cassegrain on a very solid german mount. I bought this from David for £15. I remember going to his home to collect it one lunchtime. It was quite a few miles from Walkergate in the East end of Newcastle to North Walbottle beyond the North west outskirts. David must have been in a hurry and was stopped by the law for speeding. Even then he maintained his good humour.

Also in the depths of the plan drawers were some of David’s drawings. The one I remember most was of a 40" mirror (I think) on the optical shop floor but smashed to thousands of pieces. A very sad sight – this reminded me of the day when on of the technicians was inspecting a flat. This was a large window of fused quartz- about 1.5 meter square and about 30cm thick – for the CERN particle accelerator at Geneva. Anyway the inevitable happened. The window was finished and was having a final inspection when a 6" steel rule dropped out of his top pocket onto the surface. Back to fine grinding!

There were other drawings and photographs of female nudes. David always liked the female form. At home his private optical shop was also a photographic studio (I remember the photoflood lamps inside large white paint cans.) His camera in those days was the Agiflex – one of the early 2¼" square SLRs. He used these photos and drawings and also worked from life to produce sculptures. Female heads, torsos and bodies. (My memory is a little rusty but I think these were cast from clay originals – rather than carved stone or wood.) David always thought of optical work as a form of sculpture. Somewhere within a blank there was the perfect paraboloid and his mission was to reveal it. On David’s desk there was always a small book - the Rubayat of Omar Khayam. He would often read a passage from it.

It was always interesting to wander to one of the outbuildings where David’s telescope was stored. This was the Calver 24" Newtonian originally at the observatory of the Rev Espin in Tow Law near Durham. This telescope was later given/loaned? to Newcastle University where I think it is still used at the Close-House research station. Also in this room were the central holes from some of the large mirrors. These were pretty solid lumps of glass.

David would often discuss meteor work. Various plans included a dedicated Schmidt meteor spectrograph and on smaller scale a roll film camera with objective prism but with a constantly rotating motor on the film wind so that a film could expose through a whole night without sky fog affecting any area too much. This was an era before camera motor drives were common.

David would often fantasize on telescope optics. He would postulate a pinhole telescope - long focus pinhole magnified by a short focus pinhole, and would consider ending diffraction effects by having a mirror without an edge – or with the coating becoming less reflective over the radius – perhaps unrealistic, but fun to think of. He did build a solar prominence telescope ( I think a quartz monochromator based in the one in ATM2). In later years he made a number of apo refractors built mainly from very high quality quartz produced just a couple of miles away from the Grubb Parsons works – the Thermal Syndicate at Wallsend.

David had many other interests. One was drag-racing. He dug a pit in his garage so that he could work on a dragster project which I seem to recall was based on quite a big truck engine. He was also a keen pistol shooter. He once opened up his gun cabinet (I don’t suppose you can do that at home now) and showed me an array of exotic and deadly looking weapons.

The 98" Isaac Newton Telescope was the current job for most of my time at Grubb Parsons. Every morning for the 7.30 start you would walk in the assembly hall under the bulk of the INT on its huge polar disc, then through to the main mechanical workshop where smaller telescopes were being built – typically 36" for the Jungfraujoch Observatory. You would clock in then into the glass shop.

At one end of the shop there was David’s office, near that the office of Stevie Baker – the foreman (a compulsive whistler). Steve’s office was shared by Mina (Whilhelmina?) She would always have strict control of the spherometers and the tables translating spherometer readings into focal length. There was another office with a set of polishing machines which was the haunt of Bob Martin. He was the expert in producing prisms or filters/windows from exotic materials like lithium fluoride or rock salt.

Further down the shop were the diamond generating tools and saws, then more polishing machines – one or two to handle metre range optics. Along the whole length of the shop was the testing tunnel where you would perform Foucault knife-edge testing. As you homed in on the perfect figure you would use a wavefront shearing interferometer to photographically test your mirror.

At the far end of the shop was the area where an old boy would make slabs of pitch ready to be cut into squares to make polishing laps. And then beyond that area were the large polishing machines. There was an eight foot machine and then further through was the 20 foot machine where all of the GP later large optics were finished.

The 98" mirror was either in this room or in the adjacent 100‛ test tower. It was always fun lifting the mirror with a crane, after a figuring run and over to the cell at the bottom of the tower. I banged my head on that mirror more than once. Then once the thermal effects of the polishing run had subsided (probably the next day) it would be up the tower to do some testing. We came into the test tower one morning to find one of the guys fast asleep under the big mirror in its cell. His wife had thrown him out and there was nowhere else to go!

David Sinden would talk about Ritchey and how most great opticians were mad to some degree. His own optical hero was Don Hendrix who figured the 120" mirror for the Lick Observatory. I believe he also did some of the final work on the 200" when it was optically finished inside the observatory. All three of those telescopes – the 98", 120" and 200" were cast at the Corning Pyrex plant in New York State as part of the materials testing for the 200" project.

David often spoke about having a tea shop in the Lake District but I guess he always found it hard to stop doing optical work.

I left the optical works in 1970 to head in other directions but over the years I always kept in touch either by phone or in occasional visits Helen and David’s home or his business premises at Byker or Newburn.The last time we spoke was probably when he was first getting ill. His great interest then was refractrometry, getting right to the heart of what happens when light meets glass