404 Remarks on Mr. J. Taylor's Paper 



of these causes has in all probability produced the several ac- 

 cidents alluded to and detailed by Mr. Taylor. This inquiry 

 is rendered more simple and easy from the circumstance of 

 the same description of boiler having been used in each of the 

 four instances. 



As I am not in a situation to prove that these accidents have 

 originated in neglect, I shall only observe under this head, 

 that as far as appearances after explosion ai'e to be relied upon, 

 they were such as to justify a suspicion that the boilers at Pol- 

 gooth and East Crennis were short of water. I do not think 

 it necessary to pursue this part of the inquiry further, because 

 I am prepared to show that the construction of these boilers, 

 and the mode of setting them, is quite sufficient to account, 

 not only for these, but for every accident that has ever oc- 

 curred with boilers of a like description. 



In boilers intended for high-pressure steam, three important 

 considerations are to be attended to : viz. the material em- 

 ployed, the form, and the mode of setting. With the experi- 

 ence we now have in these matters, no one would think of 

 using any other material than wrought iron. The form ought 

 to be such, that the expansive force of the steam can produce 

 no effect tending to change the form ; or in other words, that 

 the expansive force is equally exerted over the whole of the 

 internal surface of the boiler. This object is attained in the 

 spherical form, or the cylinder with hemispherical ends. This 

 is the form to which I give a decided preference ; not only for 

 the reasons above stated, but from the circumstance that not- 

 withstanding the smallness of diameter, a great depth of water 

 may be kept above the fire-line, — a point in my opinion of the 

 greatest importance. The diameters should be small, never 

 exceeding five feet, and any augmentation of capacity should 

 be attained by increase of length ; in this way also an increase 

 of heating surface may be obtained to any extent. 



The mode of setting boilers must vary according to circum- 

 stances; such as quality of fuel, &c. Care, however, should be 

 taken to expose as much surface to the action of the fire as is 

 consistent with the allowing of a considerable depth of water 

 above the fire-line. 



In no respect, except in the material employed, do these 

 Cornish boilers correspond with my idea of a good and safe 

 boiler. The right angles formed by the flat ends are subject 

 to an immense strain, and the angle iron introduced in these 

 parts is ill-calculated to resist it. It is well known to engi- 

 neers that angle iron will not resist the same strain, substance 

 for substance, as iron in any other form, — a fact which may be 

 accounted for by tlie distortion which it undergoes during the 



process 



