WIRELESS

Dominion, Volume 16, Issue 102, 16 January 1923, Page 5

WIRELESS

PAPERS AT SCIENCE CONGRESS

Several papers of a technical nature were read at the Science Congress on Saturday upon the subject of wireless. Mr. F. Robinson, F.R.G.S., dealt with radio directional maps, showing tho two map projections most suited for the purpose. The . two projections shown were gnomonic, whore great circles projected as straight lines, and morcators, where the great circles appeared as curves. He pointed out that since aerial waves presumably expanded in circles always oscillatory to the sphere of the earth, tho apparent direction of a message, received at a station would appear as a great circle. Hence gnomonic projection was suited to tho purpose. The lecturer then indicated thq method of constructing a gnomonic map with the special appliances necessary, and also showed the method of using a mercator map, comparing the advantages and disadvantages of both. The paper was of special interest at tho present time in view of the proposal to establish wireless directional signals from the lighthouses in New Zealand. i

Professor P. W. Burbidge (Auckland) read a paper bv Mr. AV. Green on tho measurement of the intensity of wireless signals.- This is an important subject which has practical application to tho best sites for wireless station and the best type of apparatus for installation under various conditions. A chief point of discussion was the difference of radio transmission by night and bv day, and the influence of the so-called ionised conducting layer at a height of about sixty miles in the atmosphere. The determination, of. longitudes bv wireloss was dealt with in a paper prepared by Dr. C. E. Adams, Government Astronomer in New Zealand. Proposals, he said, had beqn made by General Ferric, of Paris, for a comprehensive scheme of longitude determination by wireless of three points in tho Northern Hemirphere (Algiers. Shanghai, and San Francisco) .and of one point, in tho Southern Hemisphere , Preliminary experiments nt Wellington had proved that the wireless time signals sent by the French station nt Bordeaux were received at the observatory. Hie signals reached Wellington at about 7.30 n.m. (New Zealand time). Experiments in March, April, and Mnv In-J gave n preliminary value of the. longitude of llhr. 39min. 4.250 c., while the '■donte'l value was llhr. 39niin. 4.275e0. The adopted vnlne was determined by observations made over tho submarine cable. To carry out- the complete scheme it was essential to have nil tho observations similarly equipped with suitable telescopes, clocks, and wireless apparatus. A similar experiment carried out last December showed that signals were satisfactorily received every day, while the corresponding Morse moisageS Wero hot always read. <