Sept. 15, 1887] 



NA TURE 



tui-e 



473 



re and use of the new material to bring about the general 

 revolution which has therefore only reached its height during 

 the last few years, if indeed it is yet reached — certainly it is yet 

 far from complete. 



To turn for one moment to the last year. Since the last 

 meeting of this Section in Birmingham, the second Tay Bridge 

 has been completed, over two miles long, having occupied only 

 five years in construction. 



The Severn Tunnel, one of the most difficult pieces of 

 engineering ever attempted, has been completed and opened 

 for passenger traffic. 



The Forth Bridge, that structure the very thought of which 

 causes those who have seen the place to hold their breaths, and 

 of which the relative size may be best realized from the fact 

 that, held out in arms an eighth part of a mile long, at a height 

 of 200 feet above the sea, as a mother might hold out an infant, 

 are structures no less than the single spans of the Britannia 

 Bridge, 400 feet long. This gigantic structure, the progress of 

 which Section G has watched since the meeting at Southamp- 

 ton, has now attained its full height of 360 feet, although other- 

 wise not by any means fully formed. 



Nor, as you well know, is it by the completion and progress 

 only of great undertaking's that this year is marked in the annals 

 of engineering. It will be memorable, particularly in this dis- 

 trict, as the year of the commencement of the Manchester Ship 

 Canal, This undertaking, for which there is no precedent in 

 this country, has excited so much interest that it cannot be 

 otherwise than a matter of congratulation that a paper descrip- 

 tive of this work is to be read before this meeting by the 

 engineer, Mr. Leader Williams. 



The completion of the Tay Bridge, the Severn Tunnel, the 

 progress of the Forth Bridge, and the commencement of the 

 Manchester Ship Canal in one year and in one country is suf- 

 ficient assurance that, as yet, there is no lack of enterprise or 

 sign of falling-off in heroic undertakings ; nor are these by any 

 means the only signs of great mechanical activity, notwithstand- 

 ing the continual complaints of commercial depression. 



In one direction, in particular, after many years of progress, 

 so slow as to be something like stagnation, there has been a 

 decided advance. The steam-engine is such a familiar institution, 

 and has been for so long looked upon as the prime mover of our 

 entire mechanical system, that anything which affects its welfare 

 excites a deeper interest than would a mere mechanical advance. 

 It was therefore with anything but a feeling of pure exultation 

 that we heard and felt the force of predictions a very few years 

 ago that the days of the supremacy of the steam-engine were 

 numbered, that it would soon be a thing of the past, only to be 

 found in the museum, a relic like Newcomen's engine and the 

 stone implements by which our children would gauge the depth 

 of mechanical barbarism of the age from which they had 

 emerged. If sentiment be allowed in relation to anything 

 mechanical, it must be with a sense of relief that it is now per- 

 ceived how, so far from succumbing in the competition with what 

 threatened to be formidable rivals, the only effect has been to 

 bring about an important step in that internal development of 

 the steam-engine which has been long looked for, but the 

 accomplishment of which had for so long baffled the utmost 

 efforts to bring it to a practical issue that it was almost despaired 

 of — at least until it should be brought about by that circumstance 

 which we all dread, the scarcity of coal. 



The uppermost step of this advance yet reached is represented 

 by the triple and quadruple expansion engines. These engines, 

 of which the first seem to have been the triple engines of the 

 Propontis in 1874, designed by Mr. Kirk, the next those of the 

 steam yacht Isa, by xMessrs. Douglas and Grant in 1878, and the 

 third those of the Aberdeen, again by Mr. Kirk, in 1881, rapidly 

 sprang into favour for cargo steamers, in which they have already 

 proved of such advantage as to more than threaten the necessity 

 of another revolution in steamships almost before the last is 

 complete. Each week brings the announcement of some new 

 accomplishment in the use of higher ratios of expansion and 

 higher pressures of steam, so that while 60 or 70 pounds was the 

 maximum three years ago, we now hear of 130, 150, and 175 

 pounds ; and it is impossible to say to what they have not been 

 carried at the present moment, and with commercial success. 



There can be no doubt but that this latest step, as well as 

 those of the surface-condenser, high-pressure boilers, and com- 

 pound engines which led up to it have been the immediate 

 results of the premium on economy of coal offered by the open- 

 ing up of the long steam routes, first through the Suez Canal 



and recently round the Cape. But these steps must none the 

 less be considered as the results of the unprecedented attention 

 and labour, theoretical and practical, which has been devoted 

 to this object during the last fifty years. They have been a 

 result of the theoretical work of Carnot and Regnault, crowned 

 by the great discoveries of Joule and Meyer, and the subsequent 

 work of Rankine, Thomson, Clausens, and Hern, besides others, 

 which, about the commencement of the period I am .speaking 

 of, accomplished that complete exposition of the principles 

 underlying the internal economy of all heat-engines which have 

 since furnished incitation and guidance to practical efforts. And 

 iK)t less have they been a result of the many practical attempts 

 which have in the meantime been made to introduce similar and 

 equally effective developments in the steam-engine without wait- 

 ing till they were called forth by circumstances ; as notable 

 amongst which I may instance the labours and successes of Mr. 

 Perkins, who has experimentally developed the organization of 

 the steam-engine beyond any point it has commercially reached. 

 Each and all of these efforts has undoubtedly taken part in that 

 readiness to take the forward step, as soon as circumstances 

 were favourable, which is as necessary to development as are 

 the favourable circumstances themselves. The fact that a great 

 advance has been made in the use of higher-class steam-engines, 

 while it is the most gratifying circumstance one could have to 

 record, affords the greatest encouragement to all those numerous 

 workers for mechanical advance whose work is good, yet who 

 do not see its immediate effect. It also emphasizes the lesson 

 that the most perfect machine is that which is most perfectly 

 adapted to the circumstances under which it has to work ; and 

 amongst these circumstances is efficient attendance, which in- 

 volves sufficient knowledge of its requirements and familiarity 

 with its detail on the part of those who have it in charge ; and 

 while in a process of gradual development this education is^ 

 insured, in the case of a sudden step it is generally wanting. 



How far the present advance towards the limits to economy 

 which are theoretically evident may extend in the immediate 

 future it would be dangerous to predict. The present rate is 

 immense, and not by any means confined to the marine engine, 

 although I am not aware of any other class of engine in which 

 triple expansion has yet been adopted as a system. The recent 

 compound pumping-engines have attained to a very high organiza- 

 tion ; and even in those classes of engines where economy of coal 

 is more a matter of morality than of proved commercial import- 

 ance, as mill engines and locomotives, great activity is evident 

 in adapting and substituting compound engines, so as to allow 

 of the use of greater pressures and higher degrees of expansion. 

 The slow-breathing compound locomotive of Mr. Webb has 

 drawn many members of this Association on their way to this 

 meeting. Nor is the portable engine behind, as has been shown 

 by the recent trials of the Royal Agricultural Society at York. 

 The result of these trials cannot but offer the greatest en- 

 couragement to engine-makers of all kinds in their attempt at 

 higher organization. It is indeed difficult to say which has 

 been the most gratifying — the high state of economy which 

 these trials have shown to be realized, or the reinstitution of 

 the trials themselves after a lapse of twenty years, during 

 which interval their non- continuance has called forth but one 

 expression — that of regret. 



These almost sudden steps towards the realization of efforts 

 now extending over a century, to bring higher developments of 

 the steam-engine into practical use, have not passed without 

 notice. The interest and excitement amongst those more directly 

 acquainted and concerned with the steam-engine and the use of 

 steam are probably such as have not existed since the very early 

 days of the railway. It is not, therefore, as something likely 

 to be new to the members of this Section that I have dwelt 

 upon it. Remembering that there was another subject other 

 than actual mechanical achievements on which I was, as it were, 

 in duty bound to say something, it seemed hopeless for me to 

 attempt to touch on all the many advances towards a higher 

 degree of organization in mechanics which constitute the 

 mechanical feature of our era. I therefore have chosen this 

 decided movement of the prime mover as the most significant 

 and most gratifying, besides being of a kind the full importance 

 of which is not so likely to be generally apprehended until 

 pointed out, as the importance of advances such as the electrical 

 and metallurgical, involving some new departure or novel 

 application. 



That the character and rate of recent mechanical advance are 

 both exactly such as would be expected to follow as the result 



