SOLAR ECLIPSE

Hokitika Guardian, 2 April 1930, Page 2

SOLAR ECLIPSE

HISTORIC CHRONOGRAPH IN .WELLINGTON. DR. ADAMS’S PLANS. The historic* coronograph which was used at Sobral in 1919 by Mr C. Davidson, of the Royal Observatory, Greenwich, when making the eclipse* observations which confirmed the celebrated Einstein star-shift, has arrived in Wellington by the Corinthic. and will be used by the Government astronomer, Dr C. E. Adams, when he goes to the island of Niuafou to observe the eclipse- of the sun, which takes place on October 22.

-■ The island is situated in the Pacific about halfway between Samoa and Fiji, and has been selected as a station because the -belt of totality, or strip of the earth’s surface where the sun’s disc will be entirely obscured, runs across the Pacific in a direction approximately south-east, beginning north of New Guinea, passing between Samoa and Fij, and endng at the southernmost part of South Amerca. Mr Andrew Thomson, director of the Apia Observatory, discussed the suitbaiJity of Niuafou Island as an observing station in a report !publisl>ed fin “Popular AsStiOnpmy”. in 1928. It is considered by, far the best place that could be chosen for the work.

MATTER OF CONJECTURE. i The island is of volcanic origin, several severe disturbances having occurred there since the middle of lost century, and Dr Adams understands that it is not at present in a quiet state. It remains to be seen whether, the work of the New Zealand oxpedi-j tion will be hindered at all in this way. Even the precise position of the island seems to be . a matter of some conjecture, but is far less serious than it sounds.

The personnel of the expedition has not yet been decided upon, said Dr Adams fast week, and) it is probable that when the instruments have been assembled at the Dominion Observatory the number pf observers necessary 'to work them' will be determined and the. party made up accordingly. Captain G. W. E. Robertson, of H.M.S. Veronica, which reached Wellington’. on Friday, has supplied Dr Adams with special information about the island, and has recommended a site where the eclipse party could set up a station. The position of this site, however, according to the Admiralty chart, would be out at sea. The station he has proposed is on a spur at the north of the island about 40 feet above the sea. Unlike many other Pacific islands, Niuafou has no reef surrounding it, and the water is deep close to the shore. Dr Adams pasesd the island in 1919 when travelling with Admiral Jellicoe aboard H.M.S. New-Zealand. It is known popularly a 3 “Tin pan Island,’'’ because a native. swims out a considerable distance to the ship bearing the mail in a sealed tin‘container,

BRITISH INSTRUMENTS. • ' / The. instruments which the expedition'is to use have come from the British Eclipse Committee, a permanent : body made up of members of 'the Royal Society, and of the Royal Astronomical' Society. In addition to being used by Mr Davidson, the chronograph was used last year in the Federated Malay States by Dr J. Jackson, of the Greenwich Observatory. It is a large camera, 19 feet long, and has a lens of 4-inch apeiy ture. It will not be directed at the sun, but will lie in a horizontal position, the rays from the sun being deflected, into it by the 12-inch coelostat mirror, a device which turns accurately and follows the motion of the sun. Photographs of the sun will he taken by means of these two instruments working together. The size of the plate is to be large, 8 inches 'by 10 indhes. It has been suggested that Dr Adams should adapt a 5-inch telescope at present in possession of the observatory, and should, by means of a prism placed in front of it, take photographs of the elusive flash spectrum and of the spectrum of the corona. Other work may perhaps be added .to the programme. In addition to all the observations taken at the time of the eclipse itself, a great deal of careful work will have to he done in order to provide perfectly accurate time for the station. This Mill necessitate the use of chronometers carefully manipulated, as well as other apparatus, including complete wireless equipment. The latitude and longitude will probably be one of the first things determined. WELLINGTON OBSER VATTONS.

Dr Adams spoke of the remarkable experience of observing a solar eclipse from the top of Mount \ ictoi ia in Wellington. When quite young he watched a total eclipse from this situation, and the tremendous rush of the moon’s shadow across the earth, visible clearly from an elevated position, was a most thrilling experience, he said. The eclipse of October next will probably be photographed at its various stages with the 9-inch telescope which belongs to the Wellington €ity Council. The eclipse will begin on October 22 at 8.3 a.m. and end exactly two hours later. At 9.1 a.m. the sun will be most obscured, nearly half its surface being blocked out. No arrangements have yet boon made, said Dr Adams, as to how the party would reach the island.