Royal Institution of Great Britain, 431 



of the Seas, by Charles the Second; the Bristol, constructed in 

 1657; the Britannia in 1719, and Caledonia in 1808, were exhi- 

 bited : also models of Sir Robert Seppings's mode of ship-building, 

 with the round bows and circular sterns. 



Some paste models of diamonds, remarkable for their size and 

 brilliancy, and now in the possession of Messrs. Rundell and Co., 

 were on the library table. They had been presented to the Insti- 

 tution by Mr. Bigge. 



May 23rf. 



Mr. Brockedon gave some account of a new method of project* 

 ing shot, which had been discovered by Mr. Sieviere the sculptor. 

 Mr. Sieviere had furnished Mr. Brockedon with a report of his ear- 

 liest experiments, and to some of a later date Mr. Brockedon was 

 an eye-witness. The discovery was accidentally made many years 

 since by Mr. Sieviere, who was one evening amusing himself with a 

 pewter syringe, which he had converted into a cannon, having 

 closed the discharging end of the syringe, and made a touch-hole. 

 Into this cannon he put some pinches of gunpowder, and discharged 

 the piston from it, which fell harmless at a short distance; happening 

 to invert the order of firing by holding the piston, the syringe was 

 discharged with so much violence, as to pass through the ceiling 

 and floor into the chamber above that in which he sat. He was 

 struck with the prodigious difference of effect produced, and imme- 

 diately hayi a shot cast, which in form was like a mortar : this he 

 fired from a solid mandrel, or bar swung upon trunnions, and ca- 

 pable of elevation and adjustment. His experiment succeeded so 

 entirely, that he was induced to make a shot with radiant bars, 

 which, though they added little to its weight, added much to its 

 power of destruction to rigging, &c. The weight of this shot, which 

 was of cast iron, was 15 pounds; this was discharged through a 

 bank of clay 6 feet thick, and fell 20 yards beyond it. When fired 

 again, it hit point blank at a distance of 175 yards, and was buried 

 above 3 feet in the bank ; the chamber of this shot, with which a 

 touch-hole communicated, was precisely like that of a mortar, and 

 when it was placed for firing upon the mandrel, the shoulder of the 

 chamber at the bottom of the calibre rested upon the end of the 

 mandrel. The chamber contained a charge of 1 J ounce of gunpowder. 

 An experiment was made with a shot which weighed 25 pounds, 

 but a charge of 2^ ounces of gunpowder was so great as to burst it, 

 and to throw a fragment of 5 J pounds weight to a distance of more 

 than a quarter of a mile. Subsequent experiments with shot of 



2 F 2 



