14 PRESIDENT'S ADDRESS. 



siege of Antwerp on October 8th, 1914, extended between 

 about 60 and 100 miles from the source of sound. Further 

 than 100 miles off, the sound was again audible. Sometimes 

 the " silent region " consists of patches only. In the great 

 London explosion of January 19th last, the sound areas 

 were very irregular in shape, the distance of the inner margin 

 of the silent region varying from 12 to 65 miles, and being 

 from 16 to 54 miles broad. The greatest distance at which 

 the sound was heard was 121 miles. Displays of Aurora 

 borealis were observed in Scotland on August 22nd -23rd, 

 1916, at Bristol on August 27th, and at Waterford, Edinburgh, 

 Bristol, and Oxford on January 4th, 1917. 



ELECTRICITY. 



The subject for the Cecil medal which is awarded this 

 year, viz. : " The more recent applications of Electricity 

 in the present war, especially in the treatment of diseases 

 and wounds arising therefrom," has brought much interesting 

 information in the papers submitted for the competition, 

 shewing the great part played by electricity in the war. 

 There are also many developments of it which it is important 

 to keep secret, so that competitors who happen to be 

 acquainted with thorn through their official connection 

 with war work are debarred from referring to them. With 

 regard to other matters, a recent publication of the Survey 

 Department of Egypt gives particulars of a magnetic survey 

 which has been carried out in that country since 1908. The 

 first direct determination of the longitude of Washington, 

 referred to Paris, has been made by wireless between the two 

 places, situated 3,840 rn^es apart, the result differing from 

 the accepted longitude by about six hundredths of a second 

 only. The signals received at Paris are stated to have been 

 much clearer than those reaching America. In connection 

 with the electrification of the N.E. Railway the trials have 

 been satisfactory, a goods train of 1,400 tons attaining a 



