THE TRANSIT OF VENUS.

Otago Daily Times, Issue 3917, 5 September 1874, Page 6 (Supplement)

THE TRANSIT OF VENUS.

The London Times of July Ist has the following:—"The last but one of the Government expeditions for observing the Transit of Venus sailed from Plymouth for Christchurch, New Zealand, in the clipper ship Merope, on Saturday. Tlie party consists of Major H. S. Palmer, R.E., chief astronomer in charge ; Lieut. L. Darwin, R.E., assistant - astronomer and photographer ; Lieut. H. Crawford, R.N., assistant - astronomer ; and three non-commissioned officers of the Royal Engineers trained in the use of the photoheliograph. They take with them a large and complete equipment of huts, instruments, and stores, ot the kinds described at length in an -article in The Times of April 4th. The absolute longitude of Major Palmer's station, at or near Christchurch, will be accurately determined by a long series of observations of the moon. The station will be connected telegraphically, for difference of longitude, with the Wellington and Hutt Observatories, with the American station at Port Bluff, and possibly with those of some resident private observers. Chronometric expeditions will also be arranged between the Christchurch station and those of America on Chatham Island and of Germany on Auckland Island. Thus the whole group of Transit of Venus stations jn that region will be brought into connection with one another, and their relative longitudes be accurately ascertained. Though no change has been made in the Astronomer Royal's general plan of operations since the appearance of our article on the subject, details have been more fully worked out and all arrangements matured. The station at Alexandria will be strengthened by a private expedition, which Colonel Campbell, of Blythswpod, co operating with Sir George: Airy, purposes taking to Thebes. Captain OrdeBrowne, the chief of the head station, has already begun his preparations for determiningthe longitude of Alexandriaby telegraph direct from Cornwall. At Kerguelen Island, Port Palliser has been previously selected as the station subsidiary to that at Christmas Harbour, the final choice being left to Lieutenant Corbet, R.N., who is to have charge of the minor station. At the Sandwich Islands, wliere Captain Tupman is to be the general chief, with his station at Honolulu, there will be two satellite stations—one at Owyhee, under Professor Forbes, and one at Atooi, under Mr R. Johnson W Te have already described the ingenious model of the transit which Sir Gearge Airy devised for the use of the observing staff in their course of training at Greenwich. Similar models have since been supplied to each principal sta tion, so that our observers will be able to practise and keep hand and eye in training for the critical observation up to the very day of the transit. For the operations with the photoheliographs. M. Jaussen's appai'atus—for t iking a number of small photographs of the planet and sun's limb in very rapid'succession at the critical moments of ingress or egress —has been improved and adapted by Mr Christie, first assistant at the Royal Observatory, and with such success that fifty photographs may be taken in as many seconds on different parts of the same plate, without any sensible tremor of the instrument. While Venus is crossing the sun— i c, between her ingress and egress' —a photograph will be taken every two minutes. The albumen dry-plate process, as perfected by Captain Abney, R.E., is to bo used throughout. All the British official expeditions have now left England, except that for Egypt, which is ready, and will start in October. Each

chief of a party has been supplied with a most minute and admirable code of instructions."