September i8, 1890] 



NATURE 



499 



more difficult than they did. We are recognizing more clearly 

 than they did that all economic studies must have reference to 

 the conditionc of a particular country and time. Economic 

 movements tend to go faster than ever before, but, as Knies 

 pointed out, they tend also to synchronize ; and the economists 

 of our western countries have much more to learn now than fifty 

 yean ago from the contemporary history of other countries ; but 

 in spite of the many great benefits which we are deriving from 

 the increase of our historical knowledge, the present age can rely 

 less than any other on the experience of its predecessors for aid 

 in solving its own problems. 



Every year economic problems become more complex ; every 

 year the necessity of studying them from many different points of 

 view and in many different connections becomes more urgent. 

 Every y;ar it is more manifest that we need to have more know- 

 ledge ard to get it soon in order to escape, on the one hand, from 

 the cruelty and waste of irresponsible competition and the 

 licentiots use of wealth, and on the other from the tyranny and 

 the spiritual death of an ironbound socialism. 



SECTION G. 



MECHANICAL SCIENCE. 



OPE?iiNG Address by Captain Noble, C.B., F.R.S., 

 F.R.A.S., F.C.S., M.lNST.C.E., President of the 

 Section. 



In taking over the chair of this Section from my distinguished 

 predecessor, I cannot but feel myself to some extent an intruder 

 into 'ihe domain of mechanical science, and I am conscious that 

 the cffice which I have the honour to hold would have been 

 more worthily filled by one of the great mechanicians who have 

 won for the town in which we hold our meeting so widespread 

 a reputation. 



I can truly say the claims on my time are so considerable that 

 I should not have ventured to appear before you in the character 

 of President of this Section had it not been for my desire to 

 afford what little support might be in my power to my friend 

 the President of the British Association, with whom for so long 

 a period I have been associated by so many ties. 



I believe I should have consulted best both my own feelings 

 and your patience by merely opening the Section in a formal 

 manner, and proceeding at once to the business of the meeting. 

 One of my predecessors, however, has pointed out that Sir F. 

 Bramwell, whose authority is too great to be disputed, has ruled 

 that to depart from the time-honoured practice of an address is 

 an act of disrespect to the Section — a ruling which has, without 

 cavil, been accepted. 



I therefore propose to direct your attention, by a few brief 

 remarks, to that branch of mechanical science with which I am 

 best acquainted. I shall endeavour to show the great indebted- 

 ness of the naval and military services to mechanical science 

 during the period with which I have been more or less con- 

 nected with them, and the complete revolution which has in 

 consequence resulted in every department and in every detail. 



But before commencing with my special subject, it is im- 

 possible that I should pass over in silence the great work which 

 has excited so much interest in the engineering world, and 

 which, since we last met, has, with formalities worthy of the 

 occasion, been opened by H.R.H. the Prince of Wales. 



It is in no way detracting from the merit of the distinguished 

 engineers who have with so much boldness in design, with such 

 an infinity of care in execution, with so much foresight in every 

 detail, given to the country this great monument of skill, if I 

 venture to point out that, without the great advance of me- 

 chanical and metallurgical science during the present genera- 

 tion, and the co-operation of a host of workers, a creation like 

 that of the Forth Bridge would have been an impossibility. 



The bridge has been so frequently and so fully described that 

 it is unnecessary in this address I should do more than draw 

 your attention to some of its main features. 



The bridge, with its approach-viaducts, has a total length of 

 8296 feet, or nearly a mile and six- tenths; and this length com- 

 prises two spans of lyiofeet, two of 680^ feet, fifteen of 160 

 feet, four of 57 feet, and three of 25 feet. 



The deepest foundation is 90 feet below high-water mark, and 

 the extreme height of the central position of the cantilever is 

 361 feet above the same datum, making the extreme total height 

 of the bridge 45 1 feet. 



NO. 1090, VOL. 42] 



The actual minimum headway in the chaniiels below the 

 centre of the main spans at high-water spring tides is a little 

 over 150 feet, and the rail level is about 6 feet higher. 



The weight of steel, nearly all riveted work, is 54.076 tons, 

 and the amount of masonry and concrete 4,057,555 cubic feet. 



It is difficult, even for experts, fully to appreciate the stu- 

 pendous amount of work indicated by these figures. During the 

 Paris Exhibition the Eiffel Tower justly excited considerable 

 admiration, and brought its designer into much repute ; but that 

 great work sinks altogether into insignificance when compared 

 with the Forth Bridge. 



Conceive, as I have heard described, the Eiffel Tower built, 

 not vertically, but horizontally ; conceive it further built without 

 support, and at a giddy height over an arm of the sea. Such a 

 work would do little more than reach half across one of the 

 main spans of this great bridge. 



Those only who have had work of a similar nature can fully 

 appreciate the innumerable experiments that must have been 

 made, and the calculations that must have been gone through to 

 secure the maximum attainable rigidity both with respect to the 

 strains induced vertically by the railway traffic and its own 

 weight, and horizontally by the force of gales. 



The anxiety as to the security of the erection might well 

 daunt the most skilful engineer. We are told that, apart from 

 the permanent work, many hundreds of tons of weight in the 

 shape of cranes, temporary girders, winches, steam boilers, rivet 

 furnaces, and riveting machines, miles of steel-wire rope, and 

 acres of timber staging were suspended from the cantilevers. A 

 heavy shower of rain would in a few minutes give an additional 

 weight of about 100 tons ; and in their unfinished state, while 

 approaching completion, the force of any gale had to be 

 endured. 



I trust that, as the Forth Bridge has been a great engineering, 

 it may likewise prove a financial success, and I feel sure that all 

 who hear me are rejoiced that it has pleased Her Majesty to confer 

 the distinguished honours she has awarded to Sir John Fowler 

 and Sir B. Baker — honours, I may add, that have rarely been 

 more worthily bestowed. 



Let me turn now to the subject on which I propose to address 

 you ; and I shall first advert to the change which within my own 

 recollection has taken place in that service which has been the 

 pride and glory of the country in time past, and on which we 

 must rely in the future as our first and principal means at once 

 of defence and attack. 



To give even an idea of the revolution which our navy has 

 undergone, I must refer in the first instance to the navy of the 

 past. I must refer to those vessels which in the hands of our 

 great naval commanders won for England victories which lefl 

 her at the close of the great wars supreme upon the sea. 



A "first-rate" of those days (I will take the Victory as a 

 type) was a three-decker 186 feet in length, 52 feet in breadth, 

 with a displacement of 3500 tons, and she carried an armament 

 of I02 guns, consisting of thirty 42- and 32-pounders, thirty 24- 

 pounders, forty i2-pounders, and two 68-pounder carronades 

 (the heaviest of her guns was a 42-pounder), and she had a com- 

 plement of nearly 900 men. When we look at the wonderful 

 mechanism connected with the armaments of the fighting-ships 

 of the present day, it is difficult to conceive how such feats were 

 accomplished with such rude weapons. 



With the exception of a few small brass guns, the guns were 

 mere blocks of cast iron, the sole machining to which they were 

 subjected consisting in the formation of the bore and the drilling 

 of the vent. 



A large proportion of nearly every armament consisted of 

 carronades — a piece which was in those days in great favour. 

 They threw a shot of large diameter from a light gun with a low 

 charge, and their popularity was chiefly due to the rapidity with 

 which they could be worked. The great object of every English 

 commander was, if it were possible, to bring his ship alongside 

 that of the enemy; and under these circumstances the low 

 velocity given by the carronades became of comparatively small 

 moment, while the ease of working and the large diameter of 

 the shot were factors of the first importance. 



The carriages on which the rude weapons I have described 

 were placed were themselves, if possible, even more rude. They 

 were of wood, and consisted of two cheeks with recesses for the 

 trunnions, which were secured by cap squares, the cheeks being 

 connected by transoms, and the whole carried by trucks. The 

 gun was attached to the vessel's side, and the recoil controlled 

 by breeching. The elevation was fixed by quoins which rested 



