David Sinden (1932–2005): A life in optics

2021 March 28

John Nichol

Introduction

At the conclusion of a lecture described as ‘masterly and understated’, given by David Sinden at the ordinary meeting of the British Astronomical Association held on 1999 May 26, the President Martin Mobberley said that ‘we have heard a legend in the field of optics’. The conclusion of David’s talk ‘received exceptional and prolonged applause from an enthralled audience’.¹

David rose from humble beginnings to work, during his time with the company of Grubb Parsons, on some of the largest telescope optics ever made in the UK. Thomas Grubb is a name synonymous with fine-quality astronomical telescopes. The firm of that name, established in Dublin in the early nineteenth century, produced many of the finest in the world and the company was known for quality and innovation. In 1868 Thomas retired and his son Howard took over the running of the business, which in 1918 relocated to St Albans. Hard times beset the company and it was bought by Sir Charles Parsons (son of the 3rd Earl of Rosse, who was famous for his 72-inch telescope). The new business – Sir Howard Grubb, Parsons and Company (‘Grubb Parsons’) – was relocated to Newcastle in 1925. Since the last chief optician at Grubb’s (as the company was affectionately called by its employees) was David Sinden, he represented a line of highly respected opticians traceable back to Thomas Grubb and the 3rd Earl of Rosse: a pedigree of some distinction.

Beginnings

David was born in Hartlepool on 1932 Jul 31. He subsequently moved to Haverton Hill and then on to Billingham before moving to Newcastle after his appointment to Grubb Parsons. From an early age he was interested in astronomy and at the age of sixteen, encouraged by his father Fred, he made a six-inch parabolic mirror which was mounted in a telescope made with the help of his father. David made the drawings for the instrument and his father fabricated the parts. The telescope caused a stir around Hood Street, Haverton Hill, and neighbours dropped by to view the Moon, planets and stars. The local press featured the story on Friday, 1948 Nov 26, with a picture of the telescope as well as father and son.²

David was always tinkering and trying to find out ways of doing things. Leslie, David’s younger brother, recalled a couple of examples.³ On one occasion their mother asked David what he wanted for his birthday and he replied ‘a bin’, which he subsequently got. David wanted to make a casting from aluminium and devised a set-up based around a metal dust bin. The bin was pierced in several places to allow air to pass through it. A fire grate was placed in the bottom, together with some coal. A ladle containing the aluminium to be melted was fixed near the top. Finally, a vacuum cleaner was used to blow air through the apparatus to achieve a high enough temperature to melt the aluminium. The project was a success and the casting duly made.

On another occasion the outcome was not so successful. David wanted to braze some metal and came up with the idea of using a vacuum cleaner to blow air together with domestic coal gas in order to produce a flame with the required heat. The apparatus was set up, with Leslie turning on the gas and electricity and David trying to ignite the mixture; several unsuccessful attempts were made, then unexpectedly the vacuum cleaner shot off like a rocket with a tail of flames shooting from the rear. Fortunately, no permanent damage was done: the vacuum cleaner survived and David’s mother, who was not at home during the experiment, was none the wiser.

Ray Townsend, a good friend of David’s and fellow apprentice at the local Imperial Chemical Industries (ICI) works, recalls that David was a keen cyclist.⁴ Ray would pace David at ever faster speeds whilst riding his BSA motorcycle, but David was not only interested in riding quickly; he also managed to win a standing-still contest on his bicycle. I remember him telling me that he used to take part in cycling time trial events on some of the same courses that I had ridden in my cycling days. David eventually decided to get a motor between his two wheels and bought a motorcycle. Townsend recalls: ‘He bought himself an old 250cc motorbike; it was a New Imperial and it really needed some TLC. In no time he had transformed it. I’m not sure which he enjoyed the most – riding it or restoring it. Restoration or creation, be it telescopes or motorcycles, Dave had the magic touch that made it happen.’

David was also a keen amateur astronomer and the local press caught up with him once again, this time to feature the domed observatory being built in his back garden. When he applied to the local council for permission to build the observatory, he was told: ‘This is an unusual type of structure, not covered by council house regulations’. However they did not object and it was built. David was 22 years old at the time and the article mentions his girlfriend Ellen Vallely (who preferred to be called Helen), who was to become his wife. David’s other interests in astronomy included meteor observing and, in particular, photography and spectroscopy. He placed a prism in front of a photographic lens to capture the spectra resulting from bright meteors.

David became more and more dissatisfied with his experiences at ICI as an apprentice fitter; both the environment and the nature of the work were not to his liking. When he had completed his apprenticeship he left ICI and started work at Durkins, a local optician, as an expert in optical instruments (much to his father’s disapproval). In typical style he designed and built some apparatus for collimating binoculars. In a personal communication Douglas Todd, then a schoolboy, recollects visits he made to Durkins along with a friend: ‘We discovered a shop in Corporation Road, Middlesbrough called Durkins, an optician’s, which had one window full of spectacles and the other full of hand reading lenses, baby microscopes/telescopes etc. Upstairs was a shabby workshop which we found staffed by a short, dark-haired, rather enthusiastic young man just a few years older than us called ‘Dave’ – he was David Sinden. In this workshop, during late afternoons after school, he would expound on all matters relating to telescope building, mirror grinding, setting circles, mountings and simply drowned us in information! We used to leave with our heads just full of these subjects, together with wonder at his enthusiasm and obvious expertise. He tried to encourage us to buy two discs of Pyrex from a firm in Newcastle and to try our hand at grinding a 6-inch parabolic mirror. I remember that he produced a pitch blend tool, and the mirror that he had produced with it all by hand [was] of a quality that met a severe Foucault test. It was high-quality stuff which must have taken him months of work. To this day I have upstairs two lenses that he gave us and which my friend and I used to construct a small telescope, good enough to observe both the phases of Venus and about four of the moons of Jupiter.’

David was much happier dealing with that kind of work and it eventually led him to be hired at Grubb Parsons. Being located in Newcastle, some 35 miles to the north of Billingham and within commuting distance, the possibility of working for the world-renowned telescope maker was very much in David’s thoughts. He sent the firm a 6-inch mirror of his own making; it had the desired effect and he was called for an interview. On 1959 Mar 6, David wrote a letter to Grubb’s accepting the offer they had made to him – he had his dream job.

The Grubb Parsons years

1961–’66

David was quick to progress and by 1961 (aged 29) he was promoted to the post of optical workshop manager. He described himself as ‘blazing with enthusiasm’ in an interview by Mark Pendergrast for his 2003 book Mirror Mirror.⁵ At the same time, David Brown was promoted to the position of optical manager.⁶ The pair formed a formidable team and went on to produce optics for telescopes that, although not large by present-day standards, were at the time amongst the largest made anywhere. Brown was an influential figure in the development of post-war astronomical telescopes; he died prematurely at the age of just 59 on 1987 Jul 17. Brown’s contributions to astronomy earned him an honorary doctorate from Durham University in 1981.⁷ David received an honorary master’s degree from Newcastle University in 1993.

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