482 THE CENTURY, 



with some pole, for feare it be not thrust out before his 

 time : then let fire be made about the trunnion or hinder 

 part of the piece to heat the aire and water, and then when 

 one would shoot it let the pole be quickly loosened, for 

 then the aire searching a greater place, and having 

 way now offered, will thrust out the wood and the 

 bullet very quick : the experiment which we have in 

 long trunkes [tubes] shooting out pellats with aire 

 only, sheweth the verity of this Probleme.&quot; (page 173.) 



The words italicised are a complete description of the 

 Marquis s experiment, although made with a widely 

 different object, but both afford evidence of the force 

 obtainable from a small quantity of heated water, 

 the one in an imperfectly closed, the other in a well 

 closed cannon. It is remarkable how near this experi 

 ment comes to the steam-engine cylinder, piston, and 

 safety valve ; and we can scarcely believe that such 

 applications would escape the Marquis s observation, 

 when repeated and varied as was his customary course 

 in pursuing his own inquiries. 



We have thus, from 1615 to 1653, shown, what 

 sources were open to afford suggestions to the Marquis 

 of Worcester s wakeful and watchful mind, alive and 

 on the alert to seize on every hint promising some 

 enlarged and useful application. We come next to that 

 part of his own statement, where he says : u so that 

 having found a way to make my vessels, so that they 

 are strengthened by the FORCE within them, and the one 

 to fill after the other, &c.&quot; u Vessels&quot; may here apply to 

 cistems, receivers, boilers, &c., in short whatever ap 

 pliances were used. But it is usually supposed to mean 

 the boiler only, and hence the difficulty to understand 

 how its safety should increase with the increased inter 

 nal expansive force of the steam. But allowance must 

 be made for the general vagueness throughout the 



