326 FRAGMENTS OF SCIENCE. 



Aldboro' . . . .25 miles Rockets seen through a very 



hazy atmosphere ; a rumbling 

 detonation heard. 



Capel Mills . . 11 Reports heard within and with- 



out the observer's house. 

 Wind opposed to sound. 



Lawford . . . . 15^ Reports distinct: attributed to 



distant thunder. 



In the great majority of these cases, the direction of 

 the sound enclosed a large angle with the direction 

 of the wind. In some cases, indeed, the two directions 

 were at right angles to each other. It is needless to 

 dwell for a moment on the advantage of possessing a 

 signal commanding ranges such as these. 



The explosion of substances in the air, after having 

 been carried to a considerable elevation by rockets, is 

 a familiar performance. In 1873, moreover, the Board 

 of Trade proposed a light-and-sound rocket as a signal 

 of distress, which proposal was subsequently realized, 

 but in a form too elaborate and expensive for practical 

 use. The idea of a gun-cotton rocket fit for signalling 

 in fogs is, I believe, wholly due to Sir Eichard 

 Collinson, the Deputy Master of the Trinity House. 

 Thanks to the skilful aid given by the authorities of 

 Woolwich, by Mr. Prentice, and Mr. Brock, that idea 

 is now an accomplished fact ; a signal of great power, 

 handiness, and economy, being thus placed at the 

 service of our mariners. Not only may the rocket be 

 applied in association with lighthouses and lightships, 

 but in the Navy also it may be turned to important 

 account. Soon after the loss of the 'Vanguard' I 

 ventured to urge upon an eminent naval officer the de- 

 sirability of having an organized code of fog-signals 

 for the fleet. He shook his head doubtingly, and 

 referred to the difficulty of finding room for signal guns. 

 The gun-cotton rocket completely surmounts this diffi- 



