Proceedings of the Polytechnic Association. 987 



fectly and economically. lie gave up the idea of higli pressure, to 

 which he had been attached, so that lie might use a spacious but 

 weak boiler, of such form as would receive beat well, and contain 

 ample steam room and water-level. And the proportions which he 

 ostablii^hed are entitled to the highest confidence, because his whole 

 time was devoted to the perfecting of his engine, the manufactui'e 

 being left chiefly to his assistant, Murdoch, and the commercial man- 

 agement to his partner, Boulton. It was a new subject, requiring 

 new investigation throughout ; and he, of all men in the world, was 

 best endowed with the genius and experience necessary for such 

 investigations ; and the settled policy of the establishment was that 

 he should pursue them witliout interruption by other business. To 

 neglect the rules laid down by him, as the results of liis studies, 

 experiments, and practice, is injudicious in all cases in which there 

 is no special constraint. In locomotives and in marine boilers there 

 is such a constraint ; but in stationary boilers there is no absolute 

 need to make the steam room and water level less than he did. Yet, 

 biased by the surprising efRciency of the multiflue boiler in its vari- 

 ous forms, engineers liave almost entirely disregarded those rules ; 

 and the consequences have been priming, priming-boxes, super- 

 heaters, excessive throttling, and costly apparatus to remedy the dis- 

 ease ; and with all the remedies there is an acknowleged excess of 

 water in the steam from most boilers, amounting to from six to forty 

 per cent ; and in some cases boilers have been made so deticient in 

 steam room as to be utterly impracticable and unusable, and useless 

 until relieved of part of their tubes. 



" But of all boilers the worst, in deficiency of steam room and sepa- 

 rating surface, are the safety-boilers made up of small tubes, with the 

 water inside. Ogle & Summers' steam-carriage boiler cou^ not be 

 worked at less than. 240 pounds pressure ; and Dance & Field's steam- 

 carriage boiler wasted so much water that it was practically inefhcient. 

 And we have now before us boilers unexceptionable as to safety, 

 which are so defective as to dryness of steam that they cannot do 

 hard work with economy, and are not likely to supersede unsafe 

 boilers, except in cases where explosions would involve unusual losses. 

 At various times I have recommended this class of boilers, on account 

 of their safety ; and I think no prudent person will say that they 

 are not entitled to preference, notwithstanding these defects ; but 

 they ought to be made as good as any boilers, in economy, aud 

 security against minor derangements. 



