626 



SCIENCE PROGRESS 



the air was more nearly calm, but what wind there was came 

 from a southerly direction. x 



The sound-areas of the great munitions explosion which 

 occurred in East London on January 19, 191 7, are drawn more 

 completely, and with much greater accuracy. They are shown 

 in Fig. 2. The inner sound-area contains 3,390 square miles, and 

 is of unusual form. It is distorted in two directions, extending 

 to the east-south-east as far as Canterbury (48 miles from East 



Fig. 1. 



Sound-area of Spithead minute-guns, February i, 1901. 



London), and to the north-west as far as Wellingborough (66\ 

 miles) ; while, towards the north-east and south, its boundary 

 passes within 20 and 19 miles respectively of the ruined factory 

 at Silvertown. The outer sound-area is of greater extent. Its 

 length from near Nottingham to the east coast of Norfolk is 

 131 miles, and the area covered by it is 5,000 square miles. 

 The most distant place at which the explosion was audible is 

 128 miles from East London. The width of the intervening 



1 " On the Audibility of the Minute-guns fired at Spithead on February 1, 

 1 90 1," Knowledge, vol. xxiv, 1901, pp. 124-5. 



