173 MR. J. C. DYER ON THE ORIGIN OF 



cavities at eacli end of the tubes for receiving the water 

 (by a force-pump at one end), and for emitting the steam 

 at the other end. 



This tubular boiler^ with its induction and eduction 

 chambers^ was fixed in the middle of a furnace, for the 

 heat to act directly on the water in the tubes, the flame 

 circulating around them before passing off; thus, as Mr. 

 Perkins phrased it, " the water could be made red-hot, and 

 flash into steam of force exceeding that of gunpowder.^^ 



He had then a gun-barrel fixed, with the breech end 

 open just opposite the valve opening from the steam- 

 chamber, and a moving apparatus for conducting the balls 

 in rapid succession into the space between the end of the 

 barrel and the outlet for the steam, so that by having the 

 balls brought between the breech and the steam-valve, 

 the latter, opening at the same time, allowed the steam to 

 issue and propel the balls through the gun in rapid suc- 

 cession, and with a force equal to the elastic pressure of the 

 steam ; and this, of course, might be continued as long as 

 the heat from the furnace could maintain the required 

 pressure. 



By experiment he found that from fifty to a hundred 

 balls a minute could be shot forth to the end of the trial 

 ground (some hundred yards, I believe) , and made to strike 

 a target with a force nearly or quite equal to those pro- 

 jected by ordinary gunpowder. With these means of rapid 

 supply of balls and steam, by having a number of guns, 

 say ten, so fixed to exits of steam from one furnace and 

 tubular boiler, it is obvious that some 500 to 1000 balls 

 might be discharged per minute, which would constitute a 

 very formidable battery, compared with the most rapid 

 firing before known. 



These experiments were witnessed by the Duke of Wel- 

 lington and many other eminent men, who took great 

 interest in them. The causes that prevented their adoption 



