To study and encourage popular interest in all branches of Science.

Newsletter December 2010


The President and Council wish all Members a Merry Christmas and a Happy & Healthy New Year

Tempus fugit! The 'arrow of time', perhaps accelerated by 'Dark Energy', speeds on relentlessly and yet another year approaches its end. And what a year it has been for the Society. In April 2010 we celebrated the centenary of the foundation of the Observatory and the Met. Station. I doubt that the 'founding fathers', Col. Henry Heberden, Philip Vizard, Patrick Hepburn, Clement Bartrum et al, could have imagined that the Society they created to promote the study of science would be thriving a century later and they could never have imagined the discoveries made by science in such a comparatively short time.

The reason that the Society continues to flourish is due to the enthusiasm of its Council and membership and the generosity of our visiting lecturers. I take this opportunity to thank you all for your support in 2010 and express the hope that it will continue into the foreseeable future. May your thirst for knowledge never be quenched!

Our centenary year was, however, tinged with sadness by news of the untimely death of Caesar Kamieniecki who served as Minutes Secretary on the Observatory Sub-Committee and was an Observatory Demonstrator for over 30 years. Our thoughts are with his family at this time.

Doug. Daniels (HSS President) December 2010

N.B. There are two special events taking place in early January. Please see page 6 for details

The first lecture meeting of 2011 will take place on Thursday January 20th when Dr. Dewi W Lewis will be talking on the subject of 'ZEOLITES — MAGIC ROCKS.' I look forward to seeing you at the meeting. In the meantime, here is a little light reading matter to keep the 'grey cells' occupied during the 'festive season'.

GEOENGINEERING

Peter R Wallis

The argument about geoengineering continues. In the US two official reports have been published, including a Congressional analysis calling for federal research. In his foreword to the report, Burt Gordon writes, "If climate change is one of the greatest long-term threats to biological diversity and human welfare, then failing to understand all the options is also a threat".

On the other side participants in the international Convention on Biological Diversity (CBD), held in October in Nagoya, Japan, included in their agreement a moratorium on geoengineering "until there is adequate scientific basis on which to justify such activities and appropriate consideration of the associated risks". They grant an exception for smaller studies conducted in a "controlled setting", but only if they are thoroughly assessed and "justified by the need to gather specific scientific data". Some scientists are concerned that the CBD's stance will lead to confusion and delay, although the moratorium is not expected to be in force until 2012.

Then again the Intergovernmental Panel on Climate Change is encouraging scientists to expand their geoengineering studies and is planning a meeting in June 2011 to discuss its scientific basis, its costs, impacts and side effects. Ottmar Edenhofer, co-chairman of the IPCC's working group on climate change mitigation, says that commitments to reduce greenhouse-gas emissions will probably not be enough to meet the climate goals, such as limiting global warming to 2oC over the next century. He says, "Geoengineering is one option and it should be included in a portfolio of other options". So watch this space!

THE THIRD POLE

Peter R Wallis

The North and South Poles are cold and remote, threatened by global warming. But there is also another region of similar nature in the Himalayas and Tibetan Plateau which, after the Arctic and Antarctic, has the Earth's largest store of ice; it has more than 46,000 glaciers. This has recently been called "the Third Pole". But it is also Asia's water tower, because its glaciers feed the continent's largest rivers, sustaining 1.5 billion people. Yet little is known publicly about how climate change is occurring there.

To rectify this, an international programme led by the Chinese Academy of Sciences' Institute of Tibetan Plateau Research in Beijing has been set up as the "The Third Pole Environment" (TPE); it held its second workshop in Kathmandu in October this year. Now you may remember that a claim in the 2007 report of the Intergovernmental Panel on Climate Change (IPCC) that Himalayan glaciers could disappear by 2035 was shown last year to be an error, casting doubt on the IPCC's reliability. The participants in the workshop argue however that the IPCC's broader concern about Himalayan ice was correct. It is not yet clear how fast is the loss and how it will affect water resources as there is no complete inventory of glaciers for the region and the terrain and harsh weather hamper ground measurements.

There is some evidence however and it is telling. Combining satellite and ground measurements, a Chinese team have documented some 24,300 of their glaciers. It shows that their total surface area has reduced by 17% and many have disappeared since the last inventory 30 years ago. Most of the glaciers that have been studied in the Indian Himalayas are also losing mass.

One possible cause is the deposition of 'black carbon' from fossil-fuel and biomass burning, as recorded in ice-cores from five glaciers since industrial growth in the area. Calculations suggest an increase of 12 to 34% in ice melting. As a consequence, glacial lakes are becoming larger and more numerous; their area on the plateau has increased by 26% since 1970 according to a study by the University of California and there have been more than 40 lake outbursts since the 1950s. One survey listed 20,000 glacial lakes, of which 200 were potentially dangerous and needed monitoring.

The loss of ice in the North and South Poles is of course important to the prediction of global warming and sea level, but that in the Third Pole could have a more immediate and devastating effect on the billions of people dependent on the rivers it supplies.

THE HISTORY OF THE COOKE TELESCOPE

Doug Daniels

2009 marked the 4th centenary of the invention of the telescope and in April 2010 the Hampstead Scientific Society celebrated the centenary of the foundation of its astronomical observatory. The main instrument at the Observatory is a 6-inch refractor made in about 1898 by T.Cooke & Sons of York. In 1988 the firm of Cooke, Troughton & Simms ceased trading, bringing to an end the long and distinguished history of one of the world's finest astronomical telescope makers. What follows is a brief history of that company. (The writer wishes to acknowledge 'Instrument Makers to the World' by Anita McConnell as his main reference source. D.G.D.)

In 1922 Thomas Cooke & Sons of York were merged with the old established firm of Troughton & Simms which was founded in London in 1750. Cooke Troughton & Simms Ltd. were finally taken over by Vickers in 1926 but it is the firm of T. Cooke & Sons of York that is renowned by astronomers world-wide, for the manufacture of excellent astronomical optics allied to mountings that were engineered to the highest levels of craftsmanship. Before we delve into the history of Thomas Cooke & Sons, it might be a good idea to remind ourselves about the early history of the astronomical refracting telescope.

Although glass making had been practised since about 3000 BC, it seems that the regular production of optical quality glass in Europe dates from the early 17th century. There are records of crown glass production in London by 1678, but it must have been started earlier by experimenters because of the work of Leonard Digges for example.

Leonard Digges (1520-1559), was an English scientist/surveyor. We know something of his work from the writings of his son, Thomas, who in 1571 published the book Pantometria. In this volume, Thomas describes a theodolite made by his father that used a combination of mirrors and lenses to magnify distant objects. This pre-dates the patent for the refracting telescope applied for by the Dutch optician Hans Lippershey by 68 years! (1608)

The story of Lippershey's involvement is well known, albeit a little apocryphal. It is said that Lippershey's children were playing with some lenses, and by holding up a long focus convex lens with a short focus concave lens, they magnified distant objects, effectively inventing what we would describe as the 'opera glass'. Lippershey applied for a patent in 1608, but after much legal debate the patent application was rejected.

The application of the telescope to astronomy is usually attributed to Galileo, but there is evidence that the credit should go to one Thomas Harriot (1560-1621). Harriot is also credited with the introduction of the potato to England as he was on the expedition to the Americas with Sir Walter Raleigh. Harriot became interested in astronomy when he witnessed the return of what was to become 'Halley's Comet' in 1607 and in a letter to a friend, he describes an observation of the moon made with a telescope in the same year — pre-dating the observations of Galileo by 2 years.

The problem with all astronomical refractors at that time was the use of a single plano-convex objective. This introduced chromatic aberration and surrounded bright objects with a colourful fringe. To attempt to reduce this effect, early refractors were made with very long focal lengths and were as a consequence, very unwieldy instruments. Hevelius's 8-inch telescope, for example, had a tube length of 150 feet and that was not the longest.

Newton applied his mind to the chromatic aberration problem, but was unable to solve it and in 1666, thinking laterally, he invented the reflecting telescope instead. By using a concave mirror as the objective the light only had to pass through the lens of the eyepiece and this greatly reduced the dispersion. However, early telescope mirrors were not easy to make. Initially they were cast from 'speculum metal' a bronze-like alloy which quickly tarnished and frequently had to be re-polished and re-figured. It wasn't until 1865 that Leon Foucault described a method of depositing a reflective coating of silver on to glass, opening the way for the development of the modern reflecting telescope. Until that time the refracting telescope remained the preferred astronomical tool.

It was an English lawyer, Chester Moore-Hall, who finally came up with the solution. In 1729, Hall wrote a paper describing a compound lens using glasses of different refractive indices as a possible solution to reduce chromatic aberration. And in 1758, the optician John Dolland attempted to patent the idea but in the event his patent application was unsuccessful. After 1758, in England, there were several instrument makers producing small achromatic refractors. Dolland, Tulley etc. Achromatic objectives were of small diameter as the main problem at the time was in obtaining suitable supplies of glass of consistant optical quality, free of strains and air bubbles.

This was the situation when Thomas Cooke built his first telescope in1837. Thomas Cooke was born on March 8th 1807 in the Yorkshire village of Allerthorpe. His father was a shoemaker but Thomas's interests lay in a totally different direction. Inspired by the exploits of his namesake — Captain James Cook, Thomas wanted to be an explorer. To which end he rejected cordwaining (shoe making) and studied mathematics and navigation. At the age of 17 he was all set to depart to sea, but was persuaded by his doting mother to stay and take up teaching instead by opening a village school. From 1829-1836, he continued to teach locally and as a freelance tutor in York and meanwhile continued his own studies in maths, optics and mechanics.

At about this time Cooke made himself a small telescope, grinding one of the lenses from the base of a glass tumbler. The telescope worked well and he sold it to John Phillips, the curator of the Yorkshire Museum and an active member of the newly formed British Association for the Advancement of Science, (Now the B.S.A.) which held its first meeting in York in 1831.

Phillips and Cooke became friends and Phillips helped to promote Cooke's work within the wider scientific community. This in turn persuaded Cooke to embark on a full-time career as an instrument maker. To this end Cooke borrowed the sum of £100 from his wife's uncle and rented premises at 50 Stonegate in York. His wife, Hannah, worked in the shop and also took in lodgers to help with the rent so Cooke was able to concentrate on his optical and mechanical work. But first he had to build his own screw-cutting lathe and the grinding and polishing machines needed to produce lenses.

Cooke's first commission was from William Gray, a family friend who was a lawyer with a practice in York. Cooke built a 4½ -inch equatorial refractor for Gray and by all accounts it was a fine instrument. Instruments of that size were a rarity at that time, but Cooke was soon to push the boundaries even further. In 1851 he built an equatorial refractor of 7¼ -inches aperture for Hugh Pattinson of Newcastle. Pattinson was a friend of Isaac Fletcher, a well-known astronomer who was so impressed with Cooke's work that he recommended Cooke to Airy the Astronomer Royal. At about this time Cooke also met Norman Lockyer, (later Sir Norman) and sold him a telescope for his observatory at Wimbledon.

Cooke's reputation was spreading rapidly throughout the astronomical community and there was also increased demand for spectacles and opera glasses. So Cooke decided that it was time to expand and in 1855, leaving his brother Barnard to run the shop, he purchased land at Bishophill in York where he built the Buckingham Works. This was to become one of the first comprehensive instrument manufactories in the country with its own foundry, brass, glass and wood workshops, all powered by steam engines.

In 1855 Cooke was exhibiting at the Paris Universal Exhibition where a 7½-inch clock driven refractor won him the First Class Medal and universal praise. This was to be the first of many exhibitions that Cooke attended, both at home and abroad. At the London exhibition of 1862 he won two First Class Medals for his object glasses and telescope mountings and for a turret clock mechanism of advanced design, highly praised by Charles Frodsham, the eminent London clock maker.

By 1861 Cooke was employing 26 men and 14 boys at Buckingham Works engaged on the manufacture of telescopes, mountings, turret clocks, surveying instruments, opera glasses and spectacles, and Cooke's work was being praised at the Great Exhibition. In 1860 he was summoned by Prince Albert to Osborne House to discuss the construction of an observatory for the Royal Family. The telescope, a 5¼-inch refractor was proudly exhibited in Cooke's shop window for several days prior to its shipment to the Isle of Wight.

From 1863-1869, Cooke rented a shop at 31 Southampton Street in London. He was by then a fellow of the Royal Astronomical Society, elected in 1859 and he served on the Committee from 1865-66. During this time the Works were under the supervision of his sons Thomas and Charles Frederick. Thomas specialised in optics and Charles, always known as 'Fred' was a mechanical engineer — it was a genuine family business. The Cooke business was thriving during the1860's but there was a dark cloud looming on the horizon in the form of Robert Stirling Newall.

Newall was a wealthy industrialist — a producer of wire rope which he supplied to Cooke for his turret clocks. Newall had obtained from the glass manufacturers, Chance Brothers, a pair of huge glass disks suitable to produce a lens of 25-inches in diameter. This was a true giant at the time. Newall purchased the disks for £500 — a vast sum, and he sought quotations from all the reputable telescope makers, including Grubb of Dublin and of course, Thomas Cooke. Cooke was so keen to obtain the commission that he grossly underestimated the production time of such a huge instrument and quoted a totally unrealistic delivery time of one year. In the event, it took him many years before the lenses were perfected and even more years before the mounting was finished. During this time, Newall became more and more impatient with Cooke and threats were made and funds withheld forcing Cooke into near bankruptcy at one point. Cooke had bitten off more than he could chew. With a tube length of 32 feet, the instrument was too large to be assembled in the factory and had to be erected in the open air and it remained unfinished at the time of Cooke's untimely death in 1868. The years prior to Cooke's death were troubled by further problems. At the Great Exhibition, a certain Lt. Colonel Strange had seen Cooke's exhibit and wanted Cooke to manufacture a whole range of precision surveying instruments for the government to use in India. Cooke had no precision dividing engine at that time but Strange persuaded him to build one. In 1864, Cooke received an order for 16 precision theodolites. This was to be the first of many such orders to come from the government. But all this work coupled with the worry concerning the Newall telescope must have been a great strain on Cooke's health. The dividing engine was finished shortly before his death on 19th October 1869 at the age of 62.

Problems continued after Cooke's death. Without Thomas Cooke's guiding hand, the theodolites were found to be poorly divided and further orders were cancelled. Also at that time the works were engaged on building two transit instruments for longitude determination also destined for India. It took 3 years to complete this order and there were problems with one of the instruments when it arrived damaged and it had to be repaired locally.

Cooke's death put the company into turmoil. His will left everything to his widow and she was soon under pressure from Newall who attempted in 1879 to force the business into liquidation. Fortunately, a wealthy industrialist, Sir James Meek, the thrice Lord Mayor of York, came to the rescue and purchased the business, selling it on to James Wigglesworth, who was a family friend and the owner of a fine 6-inch refractor made by Cooke in 1853. In 1879, Wigglesworth went into partnership with Cooke's sons and after his death in 1888 his son Robert purchased the business for £4000 and remained a partner until the business became a limited company in 1897.

In 1870, the Newall telescope that had been a burden for so long was finally erected at Ferndean, Newall's estate near Newcastle. For a very short time it was the largest refractor in the world but it was to lose the title just a year later when the Washington Naval Observatory in the USA took delivery of a 28-inch refractor built by Alvan Clark.

After Newall's death in 1889, the telescope was transferred to Cambridge University Observatory where Newall's son Hugh was to become Professor of astrophysics. It was used in Cambridge until the1950's, after which time it was sold to the Greek National Observatory at Athens, where it remains to this day.

The end of the nineteenth century saw an upsurge in observatory construction both at home and abroad, and equatorial refractors continued to be the mainstay of the company's business, but orders for surveying equipment were still coming in. Many were used in the survey of India and in 1884 work began in Scotland on the Forth Bridge. Once again the orders for levels and theodolites came flooding in. Overcoming the earlier dividing engine problems, the Cooke instruments were once again lauded for their superb accuracy and quality of construction.

Cooke's now began to branch out, building observatory domes .as well as telescopes. Frederick Cooke devised a novel construction using papier mache panels and in 1893 they built the famous 'onion' dome for the Royal Observatory Greenwich. By the end of the century, Cooke domes could be found in astronomical observatories throughout the British Empire and beyond.

The latter part of the nineteenth century also saw rapid developments in Africa. Gold was discovered in 'them thar hills' and along with it the need for surveying instruments. Once again Cooke's order books bulged; they even opened a South African branch in Cape Town. By the end of the nineteenth century Cooke's had also diversified into military equipment and held patents for gun-sights and range finders, some of which saw action in the Boer war, which lasted until 1902.

In 1897 the company became a 'limited liability company' and after Fred's retirement in 1894, the optical department was in the hands of Dennis Taylor and was soon steered in a new direction — towards the new developments in photography. Cooke's soon devised a special 3 element lens that improved definition over a wide field. In 1893 it was awarded the Royal Photographic Society's medal for excellence. It was also in 1897-98 that Cooke's were asked by John Franklin-Adams to produce lenses for the proposed standard instruments to undertake a complete photographic survey of the heavens — the Franklin Adams Chart.

By the dawn of the 20th century, Cooke's was still a viable business, continuing to build astronomical telescopes, observatory domes, surveying instruments, military equipment and photographic lenses. In 1914 the First World War began and in 1915 Vickers acquired a 70% holding in the company, which began to concentrate on military equipment. Then after the war in 1922, Cooke's bought out Troughton & Simms to become Cooke, Troughton & Simms Ltd., operating under the Vickers banner where it remained producing a wide variety of optical equipment until final closure in 1988. — 'sic transit gloria mundi'.

To astronomers, both professional and amateur, the name Thomas Cooke of York will always be associated with equatorial refractors made during the 'golden period' at the end of the nineteenth century. They were made to the highest optical and mechanical standards which few if any instruments have equalled. My own 45 years experience with the Hampstead telescope has led to enormous respect for Cooke's work. The long focal length refractor is the ideal instrument for planetary and lunar studies and I have found few telescopes of equal aperture that can outperform it.

Our 6-inch Cooke refractor was manufactured in about 1898 and has been in use at the Observatory since 1923. It was finally donated to the Society by its owner George Avenell in 1928. It was originally mounted on a Cooke equatorial mount that was built to carry a 4-inch telescope. This mount was replaced with a stronger mount built by member Terry Pearce in 1976 and modified by Doug Daniels in 1980. At that time it was fitted with a new large diameter worm and wheel made by the late Hon. Member Ron Irving and the drive updated with a stepper motor drive unit designed and built by member Paul Clements. The Observatory, which celebrated its centenary in April 2010, continues its tradition of making this fine instrument freely available to visitors on public open nights throughout the winter months in accordance with the aims of the founders of the Hampstead Scientific Society — 'to promote an interest in all branches of science equally for the layman and the specialist.' During our centenary year some 1000 visitors to our Observatory took advantage of this unique facility, a service we can justly take pride in.

Forthcoming special events in January

On January 3rd-5th, BBC2 will be transmitting a series of programmes under the title of STARGAZING LIVE. The programmes will be hosted by Prof. Brian Cox and the timing has been arranged to coincide with the partial Solar Eclipse on Jan 4th , the Quadrantid Meteor shower — maximum also on Jan 4th and the Jupiter/Uranus alignment over the following few days. The programmes are designed to increase public awareness of astronomy. The HSS will be taking part in this event. The partial Solar Eclipse takes place at sunrise when from London, 67% of the solar disk will be obscured. Because a low south eastern horizon will be required, viewing will take place on Parliament Hill and not at the Observatory. Anyone interested please contact Simon Lang for details:- hampsteadobservatory@mulberry.myzen.co.uk.

On Saturday January 8th at 3:00 pm by kind arrangement with Peter Hingley, members are invited to visit the library of the Royal Astronomical Society at Burlington House Piccadilly. Members wishing to attend this visit should register their interest by contacting Doug Daniels as there are a limited number of places available:- starfields@tiscali.co.uk or by 'phone:- 020 8346 1056

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