56 



NATURE 



{May 1 8, 1876 



curator thoroughly competent for such a charge, but I 

 abstain from entering prematurely into further details. 



And now let me turn in conclusion to one more aspect 

 of this great undertaking. We have here collected not 

 only the instruments which represent the most advanced 

 posts of modem science, but we have not a few of the men 

 whose genius and perseverance have led the way thither ; 

 men who stand in the forefront of our battle against ignor- 

 ance and prejudice and against the host of evils which a 

 better scientific education must certainly dispel ; we have 

 men whose powers are competent for, and whose very pre- 

 sence is an inspiration to, further progress. But, while tak- 

 ing this first opportunity of offering them a hearty welcome, 

 I shall however best consult both their feelings and your 

 wishes by abstaining from any panegyric upon them in 

 their presence, and by giving them an opportunity of 

 speaking, and you of hearing them, upon some of their 

 own subjects in illustration of the remarkable instruments 

 which they have with so much pains and trouble brought 

 under our view. 



SECTION— MECHANICS. 

 opening Address by Dr. C. W. Siemens, F.R.S. 



In opening the proceedings of the Conferences regard- 

 ing Mechanical Science, it behoves me to draw attention 

 to the lines of demarcation which separate us from other 

 branches of natural science represented in this Exhibi- 

 tion. 



In the Department of Applied Science we have col- 

 lected here apparatus of vast historical interest, including 

 the original steam cyUnder constructed by Papin in 1690, 

 the earliest steam-engines by Savery and by James Watt, 

 the famous locomotive engine the "Rocket," by which 

 George Stephenson achieved his early triumphs, as well 

 as Bell's original marine engine, and a variety of models 

 illustrative of the progress of hydraulic engineering and 

 of machinery for the production of textile fabrics. In 

 close proximity to these we find a collection of models 

 illustrative of the remarkable advance in naval architec- 

 ture which distinguishes the present day. 



It would be impossible to deny the intrinsic interest 

 attaching to such a collection or its intimate connection 

 with the progress of pure science ; for how could science 

 have progressed at the rate evidenced in every branch of 

 this Exhibition, but for the great power given to man 

 through the mechanical inventions just referred to. Yet 

 were Mechanical Science at these Conferences to be 

 limited to the objects exhibited in the South Gallery (and 

 separated unfortunately from apparatus representing phy- 

 sical science by lengthy corridors filled with objects of 

 natural histery), we should hardly find material worthy to 

 occupy the time set apart for us. But, thanks to the 

 progress of opinion in recent days, the barrier between 

 pure and applied science may be considered as having no 

 longer any existence in fact. We see around us practi- 

 tioners, to whom seats of honour in the great academies 

 and associations for the advancement of pure science are 

 not withheld, and men who, having commenced with the 

 cultivation of pure science, think it no longer a degiada- 

 tion to follow up its application to useful ends. 



The geographical separation between applied science 

 and physical science just referred to, must therefore be 

 regarded only as accidental, and the subjects to be dis- 

 cussed in our section comprise a large proportion of the 

 objects to be found within the rooms assigned more par- 

 ticularly to physics and chemistry. Thus all measuring 

 instruments, geometric and kinematic apparatus, have 

 been specially included within our range, and other 

 objects such as telegraphic instruments, belong naturally 

 to our domain. 



With these accessions, mechanical science represents a 

 vast field for discussion at these conferences, a field so 

 vast indeed that it would have been impossible to discuss 



separately the merits of even the more remarkable of the 

 exhibits belonging to it. It was necessary to combine 

 exhibits of similar nature into subdivisions, and the Com- 

 mittee have asked gentlemen eminently acquainted with 

 these branches to address you upon them in a compre- 

 hensive manner. 



Thus they have secured the co-operation of Mr. 

 Barnaby, the Director of Construction of the Navy, to 

 address you on the subject of Naval Architecture, and of 

 Mr. Froude to enlarge upon the subject of fluid resist- 

 ance, upon which he has such an undoubted right to 

 speak authoritatively. Mr. Thomas Stevenson, the Engi- 

 neer of the Northern Lighthouses, will describe the 

 modem arrangements of Dioptric lights, which mark a 

 great progress in the art of lighting up our coasts. Mr. 

 Bramwell has undertaken the important task of ad- 

 dressing you on the subject of Prime Movers, and Prof. 

 Kennedy upon the kinematic apparatus forwarded by 

 Prof. Reuleaux, of Berlin. M. Tre<;ca will bring before 

 us his interesting subject, the flow of solids. Mr. William 

 Hackney will address you upon the application of heat to 

 furnaces, for which he is well qualified both by his theo- 

 retical and practical knowledge. Mr. R. S. CuUey, Chief 

 Engineer of the Postal Telegraphs, will refer you to a 

 most complete and interesting historical collection of 

 instruments, revealing the rapid and surprising growth of 

 the electric telegraph. 



Measurement. — Regarding the question of measure- 

 ment, this constitutes perhaps the largest and most 

 varied subject in connection with the present Loan Exhi- 

 bition. In mechanical science, accurate measurement is 

 of such obvious importance, that no argument is needed 

 to recomir.end the subject to your careful consideration. 

 But it is not perhaps as generally admitted, that accurate 

 measurement occupies a very important position with 

 regard to science itself, and that many of the most 

 brilliant discoveries may be traced back to the mechanical 

 art of measuring. In support of this view I may here 

 quote some pregnant remarks made by Sir William 

 Thomson in his inaugural address delivered in 1871 to 

 the members of the British Association, in which he says — 

 " Accurate and minute measurement seems to the non- 

 scientific imagination, a less lofty and dignified work than 

 looking for something new. But nearly all the grandest 

 discoveries of science have been but the rewards of accu- 

 rate measurement and patient long-continued labour in 

 the minute sifting of numerical results. The popular idea 

 of Newton's grand discovery is that the theory of gravi- 

 tation flashed upon his mind, and so the discovery was 

 made. It was by a long train of mathemetical calculation, 

 founded on results accumulated through prodigious toil 

 of practical astronomers, that Newton first demonstrated 

 the forces urging the planets towards the sun, determined 

 the magnitude of those forces, and discovered that a force 

 following the same law of variation with distance urges 

 the moon towards the earth. Then first, we may suppose, 

 came to him the idea of the tmiversality of gravitation; 

 but when he attempted to compare the magnitude of the 

 force on the moon with the magnitude of the force of 

 gravitation of a heavy body of equal mass at the earth's 

 surface, he did not find the agreement which the law he 

 was discovering required. Not for years after would he 

 publish his discovery as made. It is recounted that, 

 being present at a meeting of the Royal Society, he heard 

 a paper read, describing geodesic measurement by Picard, 

 which led to a serious correction of the previously accepted 

 estimate of the earth's radius. This was what Newton 

 required ; he went home with the result, and commenced 

 his calculations, but felt so much agitated, that he handed 

 over the arithmetical work to a friend ; then (and not 

 when, sitting in a garden he saw an apple fall) did he 

 ascertain that gravitation keeps the moon in her orbit. 



Faraday's discovery of specific inductive capacity, 

 which inaugurated the new philosophy, tending to discard 



