256 FRAGMENTS OF SCIENCE. 



guns, and syrens have been used for this purpose; but 

 it is mainly, if not wholly, with explosive signals that 

 we have now to deal. The gun has been employed 

 with useful effect at the North Stack, near Holyhead, 

 on the Kish Bank near Dublin, at Lundy Island, and 

 at other points on our coasts. During the long, labori- 

 ous, and I venture to think memorable series of ob- 

 servations conducted under the auspices of the Elder 

 Brethren of the Trinity House at the South Foreland 

 in 1872 and 1873, it was proved that a short 5|-inch 

 howitzer, firing 3 Ibs. of powder, yielded a louder re- 

 port than a long 18-pounder firing the same charge. 

 Here was a hint to be acted on by the Elder Brethren. 

 The effectiveness of the sound depended on the shape 

 of the gun, and as it could not be assumed that in the 

 howitzer we had hit accidentally upon the best possible 

 shape, arrangements were made with the War Office 

 for the construction of a gun specially calculated to 

 produce the loudest sound attainable from the com- 

 bustion of 3 Ibs. of powder. To prevent the unneces- 

 sary landward waste of the sound, the gun was fur- 

 nished with a parabolic muzzle, intended to project the 

 sound over the sea, where it was most needed. The 

 construction of this gun was based on a searching series 

 of experiments executed at Woolwich with small mod- 

 els, provided with muzzles of various kinds. A draw- 

 ing of the gun is annexed (p. 257). It was constructed 

 on the principle of the revolver, its various chambers 

 being loaded and brought in rapid succession into the 

 firing position. The performance of the gun proved 

 the correctness of the principles on which its construc- 

 tion was based. 



An incidental point of some interest was decided by 

 the earliest Woolwich experiments. It had been a 

 widely spread opinion among artillerists, that a bronze 



