By Lee Macdonald
Kew Observatory is close to the River Thames in the Old Deer Park, Richmond, Surrey. It is not open to the public, but can be viewed through the metal gates to its enclosure from the end of a road leading to it through the Royal Mid Surrey Golf Club. (Beware of flying golf balls!) In the middle years of the nineteenth century Kew was a major centre for research into Sun-Earth connections, geomagnetism and meteorology and from 1900 to 1902 it was briefly the first home of the National Physical Laboratory, now at Teddington.
On 3 June 1769 the second transit of Venus of the eighteenth century occurred. This event was partially visible from the UK and King George III commissioned the building of the observatory in the Old Deer Park. On 3 June the sky cleared just in time for the transit. The King, Demainbray and a small group of others successfully observed the ingress of Venus onto the Sun’s disc. In the 1770s Kew was the site of the successful testing of John Harrison’s marine chronometer that enabled sailors to find their longitude at sea.
In 1841 the government decided to stop maintaining the observatory and offered the use of the building to the Royal Society. In March 1842 the Royal Society turned down the government’s offer, but by then the Royal Society had a rival in the form of the British Association for the Advancement of Science (BAAS), who quickly made moves to acquire it. Under the BAAS, Kew Observatory was soon re-established, initially concentrating on meteorology. The main mover and shaker behind the scenes at Kew under the BAAS was the geophysicist and Royal Artillery officer Edward Sabine. As well as meteorology, in the 1840s he gradually introduced geomagnetic research at Kew as the BAAS’s limited budget allowed.
The Sun and its influence on the Earth
Soon after Kew was acquired by the BAAS, German amateur astronomer Heinrich Schwabe discovered that the number of spots seen on the Sun varies in a cycle of approximately 10 years. In the early 1850s Sabine discovered that Schwabe’s sunspot cycle exactly matched a 10-year cycle of variations in Earth’s magnetic field. Astronomers quickly became interested in observing the Sun. In 1856 the printer, chemist and amateur astronomer Warren De La Rue designed a ‘photoheliograph’, a special telescope for recording photographic images of the Sun. This was used at Kew to take daily solar images from 1859 until the early 1870s. Solar activity was measured by working out the total surface area of the Sun covered by sunspots on the photographs.
In 1859 Kew played an important role in discovering a connection between what are now known as solar flares and disturbances in the Earth’s magnetic field. On 1 September of that year the magnetometers at Kew recorded a brief but very noticeable jump in the Earth’s magnetic field at exactly the same time as a flare was observed by two amateur astronomers.
In 1860 the photoheliograph was briefly removed from Kew to a site in Spain, where De La Rue used it to take some of the first good pictures of a total solar eclipse. He used these images to show that prominences are part of the Sun and do not, as some believed, belong to the Moon.
Meteorology and the National Physical Laboratory
Ever since it was acquired by the BAAS in 1842, meteorology was a major part of the observational programme at Kew. Systematic records were kept of the main meteorological phenomena such as temperature, atmospheric pressure and humidity and experiments were made in using automatic instruments to record the weather.
Meteorology itself underwent major changes in the years after 1852. In 1854 the Board of Trade established a ‘Meteorological Department’, now known as the Met Office, initially to provide weather information to ships at sea. From the earliest days of the Met Office, Kew was vital to its work. It became the Office’s central observatory, from which its best observations were obtained. Instruments to be used on board ships were sent to Kew for testing, to ensure they all complied with the same standard of accuracy. The testing of instruments became a major part of the work at Kew, especially towards the end of the century. From the 1870s instruments verified at Kew bore a distinctive monogram, which became an international symbol of instrument quality.
Meanwhile, the BAAS was finding Kew an increasingly expensive drain on its limited finances and so in 1870 it was taken over by the Royal Society. In the 1890s calls intensified for a national physical laboratory for calibrating instruments on a large scale and establishing standards of measurement. Kew Observatory, with its existing calibration programme, was the obvious location and the National Physical Laboratory was officially established there in 1900. However, the building soon proved to be too cramped for the purpose and local residents objected to new buildings going up in the Old Deer Park, so a new site had to be found. In 1902 the laboratory was moved to new premises at Bushy House, Teddington, the headquarters of the NPL today.
Kew Observatory in the 20th century and beyond
The solar programme was moved to Greenwich in 1873 and geomagnetic observations were discontinued in 1925. In 1910 the observatory was taken over by the Met Office and it remained a major observatory and research station in meteorology for much of the twentieth century. Sadly, government cutbacks forced the Met Office to close down operations at Kew at the end of 1980. Until 2011 the building was leased by the Crown Estate (its original owner) to the holding company of Autoglass, who used it as offices. Now (2013) it is about to be converted and modernised inside, before being sold as a kind of millionaire’s dream property. As a listed building, however, its external appearance cannot be significantly altered.
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