Mr. HeiuvoocI on the E.rplntiion ofStram-Boih'ru. 40J^ 



almost immediately succeeded by an explosion." — "In tins 

 case had the rush of flaine from the fireplace any thing to do 

 with the subsequent explosion ?" I think there can be but 

 little doubt that the rush of flame was in consequence of some 

 fracture having already taken place in the boiler; probably 

 the fissure was not at first of veiy considerable size, as we 

 know that wrought iron does not break at once (as is the case 

 with cast iron), but rends. The rent being at first small, it 

 would have occasioned the rush ; but as the fissure once made 

 weakened the boiler, and the aperture not being sufficiently 

 large to permit the escape of a very considerable quantity of 

 water or steam, a moment between the gust of flame and the 

 explosion would in all pi-obability have elapsed. "And ad- 

 mitting that the steam was so far within the pressure that 

 could by mere expansive force regularly exei'ted injure such 

 a boiler, — might not the rupture be occasioned by the aid 

 that a vacuum suddenly created might produce?" That the 

 expansive force of the steam (30lbs on the inch) was not suf- 

 ficient to injure the boiler, remains yet to be proved, as Mr. 

 Taylor has not inlbrmed us how strong the boilers were. 

 Admitting the possible formation of a vacuum, it might per- 

 haps help us towards a 7C(jI knowledge of the cause : but I 

 am not aware of any circumstances which can have been there 

 in action, to which the power of forming a vacuum can with 

 any appearance of probability be ascribed. 



" Does not the bursting of one boiler after another as at 

 Polgooth, seem to indicate that exterior causes o})erated ? — Is 

 it possible to conceive, — supposing the pressure equal in two 

 boilers as at Polgooth, both being connected to the same steam- 

 pipe, — that the relative strength of the two should be so ex- 

 actly the same as that what would by mere expansive force 

 burst the one, should have the same effect upon the other?" 



Mr. Taylor informs us that the plates of which the interior 

 tubes are made ar e half an inch thick, and those of the outer 

 three-eighths of an inch. Now if we suppose each boiler to be 

 made of 200 plates, would it not be truly surprising if in 400 

 plates there were no two of the same strength, the thickness be- 

 ing the same, and (as we suppose both boilers were made at 

 the same manufactory) the quantity similar in eacli ? Here 

 then we have an expression of two known quantities only; 

 whilst if we refer the accident to the agency of an explosion 

 of coal-gas with atmospheric air, we must lake iiUo consider- 

 ation the activity of the distillatory action, the facilities of es- 

 cape ail()rde(l to the gas in cither boiler, the intensity of com- 

 bustion in the fiicplace, the influx of air, &c. which leads us 

 into a nuich more complicatinl calculation. The evidence 



Ni"dScr/rs. \'()l. 1. No. fj. Jiiur [H2'J. 'J (i then 



