256 FRAGMENTS OF SCIENCE. 



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, laborious, and I venture 

 to think memorable series of observations 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 report 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 spe- 

 cially calculated to produce the loudest sound attainable 

 from the combustion of 3 Ibs. of powder. To prevent 

 the unnecessary landward waste of the sound, the gun 

 was furnished with a parabolic muzzle, intended to pro- 

 ject 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 

 models, provided with muzzles of various kinds. A 

 drawing of the gun is annexed (p. 257). It was con- 

 structed 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 

 construction 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 

 gun produces a specially loud report. I doubted from 



