August 5, 1909] 



NA TURE 



175 



into the grand total of 1904 millions of dollars given as the 

 value of the mineral productions of the United States. 

 The same is true of every other metal on the list ; in some 

 cases, notably, perhaps, in that of aluminium, the value 

 of the metallic product is many times greater than that 

 of the mineral from which it is produced ; thus the value 

 of the aluminium produced is given as 5 million dollars, 

 whilst that of the bauxite from which it is produced is 

 about 450,000 dollars ; surely it is the latter figure, and 

 not the former, that should enter into a list of the values 

 of the mineral productions of any country. 



In the non-metallic products similar anomalies are also to 

 be met with ; cement, bricks, oilstones and millstones are 

 articles that owe a very great, if not in every case the 

 greater, part of their value to the labour, fuel, and power 

 used in their p_reparation rather than to the crude material 

 from which they are produced ; if an American sculptor 

 carves a statue out of native marble, should the value of 

 the linished statue be included in the sum total of the value 

 of the mineral resources? There can only be one answer 

 to such a rcductio ad absurdiim, and yet the principle is 

 exactly the same as that of including the value of the 

 dressed grindstones instead of that of the sandstone or 

 grit from which they are cut. 



The above are matters of principle which present, no 

 doubt, great difiiculties in arriving at a satisfactory solu- 

 tion ; the coordination of the methods of tabulating the 

 mineral productions of different countries, so as to admit 

 of just comparison, has often been tried, but has never 

 been attained successfully yet, so that all that statisticians 

 can do is to take care that they thoroughly understand 

 the differences that obtain between the various systems in 

 vogue. In other respects the present volumes are quite up 

 to the high standard that we have been accustomed to in 

 the United States Geological Survey publications. As 

 ah-eady said, they suffer from want of compression, and 

 there are many repetitions that might be avoided and much 

 superfluous matter that might well be excised. In fact, 

 they require more careful editing than they receive at 

 present, and this is all the more necessary seeing that the 

 different articles are written by different contributors, and 

 are of very unequal value. 



For example, no careful editor would pas.-: such state- 

 ments as we find under the item fluorspar, where we are 

 told that the mineral is " only slightly harder than 

 calcite, and consequently crushes easily," whereas the ease 

 or difficulty of crushing has nothing to do with hardness ; 

 and again, " When fluorspar is associated with zinc- 

 blende, complete separation of the two minerals has been 

 difficult on account of their nearness in specific gravity " ; 

 the specific gravity of fluorspar is about 3-1, and that 

 of blende about 4, a difference which should afford an 

 ample margin for successful separation in a suitable 

 appliance. 



Finally, it may be pointed out that although these 

 volumes in their final form may be considered somewhat 

 belated, no serious inconvenience results therefrom, as the 

 wise precaution is taken of issuing the various sections in 

 pamphlet form as soon as possible after the end of the 

 year to which they refer, an advance sheet of statistics 

 being, moreover, issued usually with considerable rapidity. 

 This is a procedure that might well be imitated with great 

 advantage by a good many other nations, our own not 

 excepted. Henry Louis. 



THE INSTITUTION OF MECHANICAL 

 ENGINEERS. 

 "T^HE summer meeting of the Institution of Mechanical 

 -'■ Engineers opened at Liverpool on Tuesday, July 27. 

 The president, Mr. John A. F. Aspinall, and the council 

 and members of the institution, were welcomed in the 

 lecture hall of the Municipal Central Technical School by 

 the Lord Mayor of Liverpool, Councillor H. Chaloner 

 Dowdall, and the members of the Liverpool reception 

 committee. The importance, of Liverpool as an engineer- 

 ing centre secured an attendance of nearly 500 members, 

 who participated in the excellent arrangements made re- 

 garding visits to works and excursions. The institution 

 dinner was held in the Exchange Station Hotel on Tuesday 

 evening, and the Lord Mayor and Lady Mayoress of 



NO. 2075, VOL. Si] 



Liverpool received the visitors in the Town Hall on 

 Wednesday evening. Meetings were held for the reading 

 and discussion of papers on Tuesday and Wednesday 

 mornings in the Municipal Central Technical School. 

 Brief extracts from those are subjoined. 



Locomotives designed and built at Horwich were de- 

 scribed in a paper by Mr. George Hughes, who is the 

 chief mechanical engineer of the Lancashire and York- 

 shire Railway. This company possesses 1517 locomotives, 

 of which there are about iioo in daily use. When the 

 works at Horwich were opened, Mr. Aspinall, president 

 of the institution, and at that time chief mechanical 

 engineer, resolved to introduce standardisation and, 

 wherever possible, interchangeability. Joy's v^lve gear 

 was adopted, as it was found that the mileage between 

 repairs was greater, and also that there was a slight 

 economy in coal per engine-mile. 



.\mong other types of locomotives described it is of 

 interest to note six engines which were fitted in 1902 with 

 Druitt-Halpin thermal storage tanks. Where stopping 

 places are frequent on rising gradients there is distinct 

 economy. Certain tests carried out between Salford and 

 Accrington resulted in a saving of one ton of water, and 

 under similar conditions elsewhere the saving was 12 per 

 cent. On other sections of the line, which are not so 

 favourable, the all-round economy of these engines is 

 brought down to 4 per cent. 



.\ four-cylinder passenger and express goods engine, 

 built to the author's designs in June, 1908, is also of 

 interest. Absolutely perfect balancing could have been 

 achieved without the aid of balance weights if the crank 

 angles, the disposition of the cylinders, and the weights 

 of the reciprocating parts had been arranged to neutralise 

 amongst themselves the reciprocating disturbing forces ; 

 then, by balancing the revolving masses, the variations of 

 rail load and the horizontal swaying couple would have 

 disappeared. Excepting for a slight vertical component 

 produced by the obliquity of the connecting-rod, the engine 

 would theii have been perfectly balanced. This arrange- 

 ment, known as the Yarrow-Sciilick-Tweedy system, would 

 have involved an independent set of valve gear for feach 

 cvlinder. Actually, the cranks were arranged in pairs at 

 about iSo° apart respectively, and the reciprocating 

 masses, being made equal in weight, balance each otLer. 

 The masses of the connecting-rods were divided between 

 the rotating and reciprocating masses as suggested by 

 Prof. Dalby, and the revolving masses were balanced by 

 revolving balance weights. This engine is a very steady 

 and smooth-running machine. 



The discussion centred round the important questions of 

 boiler deterioration, corrosion, and priming. Mr. Hurry 

 Riches expressed the opinion that the best way of avoid- 

 ing troubles due to the nature of the feed-water is to 

 remove the impurities before feeding into the boiler ; it 

 is, however, inadvisable to reduce the hardness of feed- 

 water below 6°. 



A paper on reinforced concrete was contributed by Mr. 

 .Arthur C. .Auden, of the firm of Messrs. William Cubitt 

 and Co. Reinforced concrete is by no means a new thing ; 

 it has passed the experimental stage, as is evidenced by 

 important structures erected in London in 1889, and still 

 in use. On the Continent equally large structures exist 

 which are now twenty-five years old, and have never been 

 strengthened or patched. Failures have occurred through 

 bad design or workmanship, but the proportion of these 

 is small. The cost of the proposed structure is affected 

 bv the cost of its constituents, and these in turn by the 

 cost nf freight and carriage. Hence the author briefly 

 classifies the materials, and gives useful hints on the 

 properties of each. 



For aggregates, the eastern counties' flint is often the 

 onlv stone available locally. Good, tough concrete can be 

 made with this, but is untrustworthy for fire-resisting pur- 

 poses, owing to its tendency to crack and " fly " under 

 heat. This tendency can be' much reduced by first crush- 

 ing all the stones. The same remarks apply to limestone, 

 a material which is not more fire-resisting after being 

 broken. As it is apt to disintegrate to powder under the 

 action of heat, it is inadvisable to use this material where 

 fire-resistance is an important consideration. Limestone 

 alwavs reouires washing before use to get rid of the fine 

 dust which covers it and prevents the cement properly 



