Explosion of an Engine-Boiler. 301 



on b(»"irfl, of whom only four remained unhurt. Nine were killed, 

 and the remainder more or less wounded ; and of the latter three 

 are since dead, the engine-man, named Diggins, being one of 

 theiu. 



As mijjlit he expected, this event has spread a very general 

 alarm, and ij'oved injurious to the business of vessels emplt^ed 

 in steam navigation ; from an idea tliat accideiits of this kind 

 cannot be guarded against, but must be expected as a matter of 

 common occurrence, from the nature of the movmg power em- 

 ployed ; especially if tlie steam engine be what is commonly 

 callei.1 a hii^h pressure engine, that is an engine worked with 

 steam of forty pounds pressure per square inch, or upwards* 

 That people ignorant of the properties and management of steara 

 should reason thus is not wonderful, but that men who call them*- 

 selves engineers should assist in propagating such errors is sur«- 

 p'ising. 



Every accident of this kind may be traced either to faulty 

 construction, or criminal mismanagement. If a boiler can be 

 made to woi k safely under a pressure cf four pounds per inch, 

 it is self-evident that one made of ten, fifteen, or twenty times 

 the strength, may be worked with equal safety under a pressure 

 of forty, of sixty, or of eighty pounds the inch. What competent 

 engineer ivould avow that he could not make a boiler sufficiently 

 strong to resist a pressure of 200, or even 300 pounds per inch ? 

 But if the safety valve of the boiler be locked doxvn, whether 

 constructed to resist four pounds or 400 pounds, what can be 

 expected but an explosion ? 



From all that we have been able to learn respecting the ex- 

 plosion at Norwich, we have no doubt whatever that it was ow- 

 ing to faulty construction, criminal hardihood of the engine-man, 

 and culpable mismanagement. The boiler was made of two kinds 

 of materials, of different expansive powers when influenced by 

 changes of temperature : this ought never to take place. The cast- 

 iron end was a fiat plate, with a double circular rim at a right angle 

 to it, like the lid of a snuff-box ; this was slipped over the end of 

 the wrought iron cylinder. Through the double rim and the 

 interposed cylinder of wrought iron were passed numerous bolts 

 from the inside, and tlicse were secured by screw-nuts on the 

 outside — that is, in such a manner that the very operation of 

 screwing home the nuts had a tendency to fracture the cast-iron 

 plate at the turn of its rim to a right angle. The space between 

 the rim and the cylinder was filled with the usual cement. The 

 plate itself was 07ib/, as we are informed, about ih7ee qvarlers 

 of an inch in thickness ! and it was usual to raise the steam to 

 a pressure of seventy pounds the inch before starting for the 

 voyage. At the time the explosion took place, the attendant 



engineer 



