282 FRAGMENTS OF SCIENCE 



local damage may be done by the explosion. The lantern 

 of the rock lighthouse might suffer from concussion near 

 at hand, and though mechanical arrangements might be 

 devised, both in the case of the lighthouse and of the 

 ship's deck, to place the firing-point of the gun-cotton at 

 a safe distance, no such arrangement could compete, as 

 regards simplicity and effectiveness, with the expedient 

 of a gun-cotton rocket. Had such a means of signalling 

 existed at the Bishop's Eock Lighthouse, the ill-fated 

 "Schiller" might have been warned of her approach to 

 danger ten, or it may be twenty, miles before she reached 

 the rock which wrecked her. Had the fleet possessed such 

 a signal, instead of the ubiquitous but ineffectual whistle, 

 the "Iron Duke" and "Vanguard" need never have come 

 into collision. 



It was the necessity of providing a suitable signal for 

 rock lighthouses, and of clearing obstacles which cast an 

 acoustic shadow, that suggested the idea of the gun-cotton 

 rocket to Sir Eichard Collinson, Deputy Master of the 

 Trinity House. His idea was to place a disk or short 

 cylinder of gun-cotton in the head of a rocket, the ascen- 

 sional force of which should be employed to carry the 

 disk to an elevation of 1,000 feet or thereabout, where, 

 by the ignition of a fuse associated with a detonator, the 

 gun-cotton should be fired, sending its sound in all direc- 

 tions vertically and obliquely down upon earth and sea. 

 The first attempt to realize this idea was made on July 

 18, 1876, at the firework manufactory of the Messrs. Brock, 

 at Nunhead. Eight rockets were then fired, four being 

 charged with 5 oz. and four with 7J oz. of gun-cotton. 

 They ascended to a great height, and exploded with a 

 very loud report in the air. On July 27, the rockets were 



