The Natal Observatory
The Natal Observatory

Then & Now: The Natal Observatory

By Frank Chemaly Time of article published Nov 21, 2020

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The Natal Observatory opened in 1882 in anticipation of the transit of Venus on December 4 that year. Its most important work was a study of the motion of the moon.

In 1882, David Gill, director of the Royal Observatory in Cape Town, asked the government of Natal to establish an astronomical observatory at Durban. In June that year he sent Robert Pett to Durban, and he chose a site in the south-west corner of the Botanic Gardens. At the time, the gardens extended up to Currie Road on Durban's Berea, and the site of the observatory was opposite where Observatory Court now stands at the corner of St Thomas and Currie roads.

The Natal Observatory

Gill invited British astronomer Edmund Nevill to take up the post of director of the observatory. Nevill landed in Durban on November 27 and, despite problems with the equipment, managed to observe the transit successfully.

The observatory was initially equipped with a 200mm Grubb equatorial refracting telescope donated by lawyer Harry Escombe, a 75mm Troughton & Simms transit instrument, a clock by Dent keeping sidereal time, and some precision clocks and other minor instruments.

Nevill remained director until it was closed in 1911, after the incorporation of Natal into South Africa in 1910.

View of the CBD from the spot where the old Observatoy was situated on Currie Road.

One of his key assistants was Mabel Grant, South Africa's first women's single tennis champion, and a meteorological and astronomical assistant who became his wife in 1894.

During the 1880s the discrepancies between the best available lunar tables (published by Hansen in 1857) and observations had become so large that navigators could no longer use the moon's position to determine their longitude accurately. Nevill first verified Hansen's treatment of lunar perturbations caused by the direct action of the sun, and then devised an improved method for calculating perturbations caused by Venus. The remaining errors he ascribed to the gravitational pull of the other planets, whose effects were very difficult to calculate. This work was published in a paper for the Royal Astronomical Society in 1885, describing the corrections required by Hansen's tables.

He next studied all available lunar observations since the middle of the 17th century and reduced them to a uniform basis. Comparing these observations to Hansen's tables, he used the discrepancies to derive the amplitudes and periods of appropriate correction terms. The tables now provided an excellent fit to all lunar observations made since 1650.

The work was ready for publication at the end of 1894, but no funds were available. Nevill pleaded for support to publish it in each annual report to the Natal government, but to no avail. In 1899 the manuscript was damaged during a rainstorm because of a leak in the observatory's roof. In subsequent years similar work was done by others, who received the credit.

The observatory was also responsible for analysing and publishing meteorological observations across the province. By 1900 there were 31 stations that submitted their observations monthly, and in 1908 Nevill wrote an article on the rainfall in Natal, in which he identified an 18-year rainfall cycle. The staff also analysed tidal observations.

After the formation of the Union of South Africa in 1910, the post of government astronomer of Natal was abolished and the observatory closed. Some of the equipment went to the Union Observatory in Johannesburg.

In 1922 the Natal Astronomical Association repaired the observatory and opened it to the public. But it was an uphill struggle to keep it going. Slowly the equipment was removed to other institutions. Later the 200mm refractor came under the control of the Natal Technical College.

All that remains today, as Shelley Kjonstad’s picture taken last week shows, is part of the foundation of a brick wall. A hundred years later, in 1982, the city laid a bronze plaque on the site where the observatory once stood.

The Independent on Saturday

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