540 REPORT— 1888. 



and minerals, including of course coal, the indices are 165 and 206, a 

 difference of 23'1 per cent. ; whilst the whole stands at 922 and 1,062, or 

 10"85 per cent., thus showing the relative proportions of the two raost 

 inaportant branches of our national industries, and the degrees in which 

 they have varied in the one year from the other. It must be remembered 

 always, however, that a vast variety of articles into which the materials 

 are converted when finished, as, for instance, apparel from cotton and 

 hardware from iron, are included in the unenumerated because we have 

 no facts as to the alterations either of quantity or price. 



Another branch of the inquiry, even as regards the export trade, would 

 require similar figures and calculations for the imports of the raw materials 

 in which we work. These are widely different in the case of the two princi- 

 pal branches, for almost all of those enumerated with textiles are of foreign 

 production, whilst those employed in the metal industries are chiefly 

 from native sources. To select for illustration the one class of cotton 

 goods, of which the chief constituent is of foreign growth. Cottons 

 altogether have an index-number of 278 out of 922 for value, and one of 

 318 out of 1,062 for volume. The imports of cotton wool (after deducting 

 the quantity sent away again in its original condition) are indicated by 

 143 for value and 166 for volume, which are very nearly one-half of the 

 whole export figures. The index for prices is almost exactly the same, 

 namely, '86 or '87, showing that there must have been a fall in the labour 

 or other elements of the cost of production in the same ratio as in that 

 of the raw material. 



These particulars are not singled out as proofs of the progress the 

 country has been making — for that would require a much more detailed 

 examination — but as instances in which the method of reduction into 

 index-numbers facilitates inquiry and exemplifies its results. For whilst 

 as regards each individual article or material its own figures furnish the 

 best means of comparison, it is only, as is well known to all inquirers, 

 by getting some common basis that we can effect the necessary addi- 

 tions, deductions, or combinations without which it is not possible that 

 the whole should be shown or general conclusions established. 



The Friction of Metal Coils. 

 By Professor Hele Shaw and Edward Shaw. 



[A communication ordered by the General Committee to be printed in externa 



among the Kej)orts.] 



OoiL friction has long been used as a powerful means of communicating 

 or retarding motion. Even where only a partial coil is employed, as 

 in the case of leather or rope belting and flexible metal brake bands, the 

 frictional resistance to be obtained by small pressures is very considerable ; 

 but where several complete convolutions are used, the effects to be 

 produced are unlimited. Thus a rope, half a turn of which is taken 

 round a post, will enable a man at one end to sustain a force thr-ee times 

 as great at the other ; but the resistance is multiplied three times for 

 each half-turn, so that in four or five turns a resistance of several hundred 

 tons might be obtained, and the result only limited by the ultimate 

 tenacity of the rope. On first thoughts, it would not be obvious that. 



