254 



TJic Country Gcntlcniaiis Magazine 



Jjarin (Engineering. 



THE increased and increasing number of 

 accidents, many of them fatal to life, 

 all of them more or less destructive to pro- 

 perty, which have characterized the use of 

 boilers of steam-engines in rural districts, 

 make it a matter of very considerable im- 

 portance that those who have them should 

 know best how to use them, so that they will 

 at once secure economy and safety in work- 

 ing. Not at present to go into a review of 

 all or any of the theories which have been 

 promulgated from time to time as to the 

 cause of boiler explosions, some of them very 

 fanciful, and obviously erroneous, all of them 

 Biore or less conjectural — since, in a matter 

 in which so many occult causes exist, con- 

 jecture is all that is left us — it will be suffi- 

 cient for the purposes we have in view if we 

 state here that the causes of boiler explosions 

 arise mainly from, first, " faults in the original 

 construction of the boiler," and, second, "faults 

 arising from the carelessness of their attend- 

 ants." However much may be the divergence 

 of opinion which exists amongst authorities as 

 to the occult causes of explosion, there is none 

 as to the fact that boiler explosions would be 

 less frequent — if, indeed, they would ever 

 occur — if they were originally well con- 

 structed, and if they were carefully attended 

 to in working. 



It is quite obvious that to go into detail in 

 the matter of safe construction of boilers would 

 be more in keeping with the requirements of 

 a journal devoted to the interests of practical 

 mechanism than this is ; we shall, therefore, 

 devote our Note chiefly to a consideration of 

 those points which are concerned with the 

 careful attendance upon boilers while work- 

 ing. It will not, however, be amiss to give a 

 hint or two as to the most recent develop- 

 ment of boiler engineering, in the direction of 

 ensuring safe boiler construction. And per- 



haps the most remarkable feature of recent 

 practice is the return to the use of cast-iron 

 in place of ^^Tought or malleable in the making 

 of boilers. Not here to enter into detailed 

 statements as to the relative value of cast 

 and wrought-iron for boiler-making purposes, 

 it is sufficient to state that cast-iron stands 

 the action of heat and flame very much better 

 than wrought-iron; and it also resists more 

 completely the corrosive action of water. 

 These facts have for long been known to 

 practical men, but the difficulty was to ob- 

 tain sufficient strength to resist the expansive 

 force of the steam with a moderate degree of 

 size and thickness, and consequent weight. 

 The difficulties surrounding the subject have, 

 in the opinion of the best authorities, been 

 overcome and obviated in the most recently 

 introduced "hollow sphere," or Harrison 

 boiler, so called from the inventor, an 

 American engineer ; the principal feature of 

 which was the result of a great number of 

 experiments instituted to ascertain the best 

 fonn in which to use cast-iron. As will be 



Fig. lo. 



seen from the engraving in fig. lo, the 

 "boiler" so-called is made up of a series of 

 " hollow cast-iron spheres" aa, joined together 

 by hollow necks, and strung, so to say, upon 



