366 



NATURE 



\Aug. 29, 1872 



whilst Brazil, Cliili, Mexico, Grenada, and otiier American Re- 

 publics liive a-lopted the metric system absolutely. 



Nor has there been less done as regards the coimge. If wo 

 compare the coins now in use all over tlie world with those in 

 use some twenty years ago it will be seen what advance we have 

 already made everywhere towards unity. Some countries, such 

 as France, Italy, Switzerland, Belgium, Greece, and Roumania, 

 have already an identical system of coinage secured to them by the 

 Coinage Convention of December 23, 1S65. The Austro-Hun- 

 garian Kmpire issues gold pieces marked 20 florins and 8 floriui, 

 enual to 25fr. and lofr. respectively. Spain issues gold pieces of 

 25 pecates, equal to the 25fr. pieces, and Sweden the Caroline, 

 equal to lofr. 



The Committee much regret that the German Empire, which 

 had recently a most favourable opportunity for extending the 

 desiied uniiormity, an object to which she has shown her 

 adherence by the adoption of the metric .system, has i-isued a 

 new gold coinage, having nothing in common either with the 

 money of the Convention of France, Switzerland, Italy, an*! 

 Belgium, or with the monetary systems of England or the United 

 States. 



During the last yeir the Committee have had communications 

 with the Indian Government on the question of introducing the 

 metric system of weights and measures int j India, tile original 

 Act by which all the weights and measures of the system were 

 introduced having been vetoed by the Home Governmen", and 

 another, limited to the weights and measures of capacity, having 

 been passed in its stead. 



The ramification of the weights, measures, and coins all over 

 the world will be fraught with immense benefit to science, 

 commerce, and civdisa'ion ; and scientific and philosophical 

 bodies of all nations have given their adhesion to it ; the com- 

 mercial classes look for it as an essential element in the economy 

 of time and the perrormance of international work, and travellers 

 all over the world regard it as the greatest boon that could be 

 conferred. Towards the attainment of this important object the 

 Metric Committee of the British Association for the Advance- 

 ment of Science have exercised an important influence. 



SECTION G— Mech.\nic.vi. SciE.vce 



Oi'ENiNG Address dy the Preside.nt, Frederick J. 



Bramwell, C.E. 



The point which I have to determine is what shall my one 

 subject be — on what shall I address you ? I have thought over 

 many subjects connected with mechanical science, but I cannot 

 discover anything more practically important than "Coal." 

 Very few matters are of greater real interest at all times to the 

 nation at large, and very few are more prominently before the 

 minds of the puldic at the present time, and certainly no subject 

 can be more appropriate for a mechanical engineer, if for no other 

 reason than this, that the steam engine is still the very crowning 

 glory of mechanical engineering, and that coal is the staff of life, 

 and, so to speak, the breath of the nostrils of the steam engine. 

 Tlie raisings of coal, which in 1855 were only 64 millions of tons 

 in Great Britain, rose to So millions in 1S60, and to loS millions 

 in lS6g ; and I will also advert to the fact that the price of all 

 kinds of coal has in the colliery districts risen, speaking in round 

 numbers, about 100 per cent, within the last twelve months, and 

 is still rising. Let us now see how we do deal with coal in those 

 cases where coal must be used; how we might deal with it in 

 such cases ; and how we might in certain instances substitute 

 other sources of power for the coal which we now consume. 

 And let us first of all consider this question of finding sources 

 other than coal for our motive power. Before the steam engine 

 was so extensively used as it now is, the wind, the force of the 

 streams, anf the force of the tide were all employed to give 

 motive power. With I'espect to the power of the wind, it is to 

 be feared it is too irregular to enable any mxnufac urer to rely 

 upon it in competition \vith the steam engine. With respect to 

 the power of our streams, the altered condition of the soil due to 

 increased drainage and cultivation has so materially interfered 

 with the regularity of their flow, that their efficiency as sources 

 of constant power is seriously diminished, while competition with 

 them by steam has become much greater than it was when the 

 water mills themselves were better off. This state of thing.s, 

 however, might be cured, and, in fact, has been cured in certain 

 districts, by the union of a large number of mill proprietors to 



form storage reservoirs, from which the water can be delivered 

 with regularity so as to give an uniform supply to the mills. 

 But the third source of water power, the tkle mill, v/hich at one 

 time was used to a considerable extent, is almost wholly discon- 

 tinued. The causes ofthis discontinuance are -sufficiently obvious. 

 The tide mill as formerly constructed could work for only a 

 limited period in each ebb, and to obtain the full elTect it had to 

 utilise both the night and the day tides. But while the tide mills 

 laboured under these disadvantages, they possessed the great 

 merit that their power, such as it was, was one that could be 

 depended on, and one which, although it fluctuated, fluctuated 

 regularly and within known and definite limits. I would suggest 

 that, in those cases where there are large manufactuiing districts 

 within a few miles of the sea, and where there is a rise and fall 

 of the tide, coupled, in the outset at all events, with natural in- 

 dentations of the coast which might be comparatively readily 

 dammed up for the storage of the water, there such storage 

 should be made that the water shou'd be set to work turbines of 

 the best kind (turbines which will work with very nearly the 

 same per-centage of the total power given out by the water at 

 any particular moment, whether they are immersed or whether 

 they are not) ; that these turbines .'>hould be employed in pump- 

 ing water at a high pressure into Armstrong accumulators ; and 

 that pipes should be laid on from those accumulators to the 

 neighbouring manufacturing town, and should there deliver their 

 power to the consumers requiring i", to be used by them in 

 water-pressure engines. Suppose a beginning were made with 

 the city of Bristol, which is no doubt a very lavourable instance 

 for the appUcation of this suggestion. Here the rise and fall 

 of the tide might safely be taken at 24 ft. Half a square mile 

 of water enclosed would, after the most lavish deductions for 

 loss, yield, in Bristol at least, 5,000 horse-power, probably suft'i- 

 cient to replace the whole of the power of thesia'ionary engines 

 now at work in Bristol. I will now consider the question how 

 coal is wasted in its use, but before doing so I will say a few 

 words upon the loss that occurs in the coal mine itself. Happily, 

 this loss has for some years past been greatly reduced. Mo:e 

 economic systems of working have prevailed, plans of dealing 

 with small coal by washing away its impurities, so as to render 

 it fit for cokeing, have been largely adopted, and thus a great 

 deal of that coal which a few years since would have remained 

 buried in the mine, as not justifying the expense of raising it to 

 the surface and of paying royalty upon it, is now brought to light 

 and is utilised. Nevertheless we know that at ordinary prices 

 of coal it is to the advantage of the colliery proprietor in many 

 instances to leave a considerable per-centage of the seams 

 that are worked rather than to entleavour to lessen that per- 

 centage by the use of a more expensive system of artificial sup- 

 port for the roof, and further that it also pays him to leave alto- 

 gether unworked very thin seams of coal. Hereafter, when coal 

 becomes scarce, there can be no question that the inhabitants of 

 these islands would be glad to make use of the nuw despised 

 unworked seams, and also to recover the buried coal of the 

 worked seams ; but such seams and such savings, although they 

 can be worked and made at present, when the mines are open, 

 if not at profit, yet with little loss, will then only be capable of 

 being reached by a reopening and pumping out of abandoned 

 mines, a process so expensive that great indeed must be the 

 need of our successors if they are compelled to resort to it. I 

 now come to the (juestion of the way in which waste occurs in 

 the use of the coals that are brought to the surface. This use 

 may be divided into two great branches — the domestic and the 

 manufacturing. I will consider first the domestic use. This is 

 a highly important branch of the subject. It is beUeved that 

 out of the total of ninety-eight or ninety-nine millions of tons of 

 coal which in 1869 were retained for home use, eighteen and a- 

 half millions of tons, about one-fifth of that quantity, were con- 

 sumed for domestic purposes (about ten millions being 

 exported). We all of us know intimately the way in which 

 coals are burnt for domestic purposes. The other way in 

 which we use coal is for purposes of manufacture, and this, 

 .again, may be divided into two branches at least — namely, the 

 coal that is employed for obtaining povver, and the coal that is 

 employed in metallurgical and other operations not immediately 

 connected with the production of power. To treat of those latter 

 cases first, they are far too numerous to be dealt with in detail, 

 and, therefore, only a few of the principal must be considtred. 

 Take the subject of coke making. I low much coal is heated in 

 clamps and in kilns to be converted into coke, and in how few 

 instances is any use made of the whole of the heat residing in the 



