40 REPORTS ON THK STATE OF SCIENCE. — 1919. 



Radiotelegraphic Investigations. — Report of the Committee, con- 

 sisting of Sir Oliver Lodge (Chairman) , Dr. W. H. Eccles 

 (Secretary), Mr. S. G-. Brown, Dr. C. Chree, Sir F. W. 

 Dyson, Professor A. S. Eddington, Dr. Erskine-Murray, 

 Professors J. A. Fleming, O. W. 0. Howe, H. M. Mac- 

 DONALD, and J. W. Nicholson, Sir H. Norman, Captain 

 H. E. Sankby, Professor A. Schuster, Sir Napier Shaw, 

 and Professor H. H. Turner. 



During the past twelve months the war-time restrictions on wireless- 

 telegraphy have continued in operation. A few statistical records 

 from British Colonial Eadio Stations have been sent regularly to the 

 Committee, and occasional information from other parts of the world 

 has been received. 



Solar Eclipse of May 29. 



In connection with the solar eclipse of May 29 the Committee 

 arranged for the carrying out of experiments on the effect of the eclipse 

 on signals ti'ansmitted across the central line. The British Admiralty 

 stations at Ascension and the Azores transmitted continuously during 

 the transit of the umbra across the Atlantic Ocean. Observing stations 

 north of the equator were for the most part asked to listen to Ascension 

 for at least an hour round about the time when the umbra passed 

 between themselves and Ascension ; observers south of the equator 

 were asked for the most part to listen to the Azores. Certain selected 

 stations north of the equator were asked to listen to the Azores, so as 

 to afford check observatio'ns upon the variations which might be 

 observed in signals jiassing across the central line of the eclipse, and, 

 similarly, selected stations south of the central line were asked to listen 

 to Ascension. The American station at Sayville also transmitted a 

 programme during a portion of the period of the eclipse, and ai'range- 

 ments were made for special experiments between Darien and the 

 Falklands, and between an Egyptian station and a South African 

 station. 



The main portion O'f the experiment hinged upon Ascension. The 

 umbral cone passed from West to East, and was expected to affect in 

 succession the strength in which signals were received at such stations 

 as Demerara, Jamaica, the stations on the coast of the United States 

 and Canada, stations in Ireland, England, France, Italy, in the Mediter- 

 ranean and Egypt. 



The shadow of the mooin struck the earth first at dawn on the coast 

 of South America and swept across the Continent in the course of half 

 an hour, at first with enormous velocity, but losing speed as the Atlantic 

 Ocean was approached. About the middle of the Atlantic Ocean and 

 near the equator the speed of the shadow was about one-third of a mile 

 per second. On crossing the African Continent from the Gulf of 

 Guinea to the Mozambique Channel the speed gi'adually increased, and 



