270 FRAGMENTS OF SCIENCE. 



rockets and of signals fired a few feet above the ground. 

 The experiments throughout were arranged and con- 

 ducted by Mr. Mackie. Our desire on this occasidn was 

 to get as near to windward as possible, but the Swale 

 and other obstacles limited our distance to 1^ mile. 

 We stood here E.S.E. from the firing-point while the 

 wind blew fresh from the N.E. 



The cotton-powder yielded a very effective report. 

 The rockets in general had a slight advantage over the 

 same quantities of material fired near the ground. The 

 loudness of the sound was by no means proportional 

 to the quantity of the material exploded, 8 oz. yielding 

 very nearly as loud a report as 1 Ib. The * aerial 

 echoes/ which invariably followed the explosion of the 

 rockets, were loud and long-continued. 



On the 17th of October, 1877, another series of ex- 

 periments with howitzers and rockets was carried out 

 at Shoeburyness. The charge of the howitzer was 3 

 Ibs. of L. G. powder. The charges of the rockets were 

 12 oz., 8 oz., 4 oz., and 2 oz. of gun-cotton respectively. 

 The gun and the four rockets constituted a series, and 

 eight series were fired during the afternoon of the 17th. 

 The observations were made from the ' Vestal ' and the 

 ' Galatea/ positions being successively assumed which 

 permitted the sound to reach the observers with the 

 wind, against the wind, and across the wind. The dis- 

 tance of the ' Galatea ' varied from 3 to 7 miles, that of 

 the ' Vestal/ which was more restricted in her move- 

 ments, being 2 to 3 miles. Briefly summed up, the 

 result is that the howitzer, firing a 3-lb. charge, which 

 it will be remembered was our best gun at the South 

 Foreland, was beaten by the 12-oz. rocket, by the 8-oz. 

 rocket, and by the 4-oz. rocket. The 2-oz. rocket 

 alone fell behind the howitzer. 



It is worth while recording the distances at which 



