RECENT EXPERIMENTS ON FOG-SIGNALS. 285 



still superior to the gun. On the 6th of August, at St. Ann's, the 4- 

 ounce and 8-ounce rockets proved superior to the siren. On the Sham- 

 bles Light-vessel, when a pressure of 13 pounds was employed to sound 

 the siren, the rockets proved greatly superior to that instrument. Pro- 

 ceeding along the sea-margin at Flamborough Head, Mr. Edwards states 

 that at a distance of 1^ mile, with the 18-pounder gun hidden behind 

 the cliffs, its report was quite unheard, while the 4-ounce rocket, rising 

 to an elevation which brought it clearly into view, yielded a powerful 

 sound in the face of an opposing wind. 



On the evening of February 9, 1877, a remarkable series of experi- 

 ments was made by Mr. Prentice, at Stowmarket, with the gun-cotton 

 rocket. From the report with which he has kindly furnished me I ex- 

 tract the following particulars. The first column in the annexed state- 

 ment contains the name of the place of observation, the second its dis- 

 tance from the firing-point, and the third the result observed : 



Stoke Hill, Ipswich 10 miles Rockets clearly seen and sounds distinctly heard 



53 minutes after the flash. 

 Melton 15 " Signals distinctly heard. Thought at first that 



sounds were reverberated from the sea. 

 Framlingham 18 " Signals very distinctly heard, both in the open 



air and in a closed room. Wind in favor of 



sound. 

 Stratford. St. Andrews 19 " Reports loud; startled pheasants in a cover close 



by. 



Tuddenham. St. Martin ... 10 " Reports very loud; rolled away like thunder. 

 Christ Church Park 11 " Report arrived a little more than a minute after 



flash. 

 Nettlested Hall 6 " Distinct in every part of observer's house. Very 



loud in the open air. 



Biklestone 6 " Explosion very loud, wind against sound. 



Nacton 14 " Reports quite distinct mistaken by inhabitants 



for claps of thunder. 

 Alboro 25 " Rockets seen through a very hazy atmosphere ; a 



rumbling detonation heard. 

 Capel Mills 11 " Reports heard within and without the observer's 



house. Wind opposed to sound. 

 Lawford Z5 " Reports distinct : attributed to distant thunder. 



In the great majority of these cases, the direction of the sound in- 

 closed a large angle with the direction of the wind. In some cases, in- 

 deed, the two directions were at right angles to each other. It is need- 

 less to dwell for a moment on the advantage of 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 

 the Board of Trade actually proposed a light-and-sound rocket as a sig- 

 nal of distress, which proposal was subsequently realized, but in a form 

 too elaborate and expensive for practical use. The idea of the gun-cot- 

 ton rocket with a view to signaling in fogs is, I believe, wholly due to 



