274 



NATURE 



[June 6, 1918 



aeam motion is mainly a local effect of this revblu- 

 ,ion. Studies of star clusters and of the comparative 

 spectra of near and distant stars have indicated that 

 the amount of absorption or scattering \Of light in 

 space must be extremely small. The 6o-in. reflector 

 has been used to establish magnitude scales over a 

 wide range, the faintest stars included being of photo- 

 graphic magnitude 201. 



Spectra of Chromosphere and Corona. — The 

 results of measurements of a plate obtained at Vavau, 

 Tonga Islands, during the total eclipse of the sun of 

 April 28, 191 1, have recently been given by the Rev. 

 Father A. L. Cortie, S.J. (Monthly Notices,* R.A.S., 

 vol. Ixxviii., p. 441). The photograph was taken with a 

 prismatic camera under somewhat unfavourable condi- 

 tions, but it extends far into the red, and twenty-five 

 chromospheric lines not previously recorded have been 

 found between A 6600 and A 7640. The majority of 

 these are probably due to iron, but there is a fairly 

 strong line at A 6941, which remains unidentified. 

 There are indications of a new coronal radiation about 

 A 7150, which is possibly related to the previously 

 known line at A 55358, in agreement with the 

 theoretical investigations of Prof. Nicholson. 



THE METRIC SYSTEM AND DECIMAL 

 COINAGE. 



NOTWITHSTANDING the growing demand in 

 this country for our adoption of the metric 

 system of weights and measures and a decimal system 

 of coinage, the Cornmittee on Commercial and Indus- 

 trial Policy after the War has reported against the 

 early introduction of both these overdue reforms. It 

 is proposed in the following commentary upon the 

 Committee's recently issued report (Cd. 9035, chaps. 

 x. and xi.) to show that the arguments upon which 

 these decisions are based are open to considerable 

 criticism. For ease in reference these comments 

 ■ generally follow the sequence of the report. 



The Metric System. 



The Result of the Permissive Act of 1897. — In its 

 historical review of the previous efforts to establish 

 the metric system in this country, the Committee states 

 that, although the use of the metric system has been 

 permissive for the last twenty years, the number of 

 metric weights and measures presented annually for 

 verification and stamping is now only about i per 

 cent, of the number of Imperial* weights and measures 

 similarly presented. The Committee has apparently 

 failed to realise that the Act of 1897 alone could not 

 possibly extend our use of the metric system, because, 

 for example, it is obviously impracticable for trades- 

 people to have two different sets of weights— in dif- 

 ferent systems — in concurrent use on their shop- 

 counters. It is also unreasonable to expect British 

 rfianufacturers to employ the metric system in their 

 workshops so long as our railways are permitted to 

 refuse consignments of their products unless the 

 Imperial equivalents of the weights and dimensions 

 are also stated. 



Further evidence of the futility of this Act as a 

 measure for encouraging the use of the metric system 

 in this country is unconsciously supplied by the Com- 

 mittee itself in its statement that even our present 

 .limited use "appears to arise mainly in connection 

 with the recent legislation of metric carat weights and 

 the adoption in the British Pharmacopoeia of metric 

 weights and measures for the prescription of doses." 

 The 1897 Act has thus proved a dead letter, and 

 further legislation is already long overdue. 



As in the case of the daylight-saving scheme, the 



NO. 2536, VOL. lOl] 



I community as a whole cannot enjoy the benefits of the 

 i metric system until its use is established by law. 



The Difficulty of Spare Parts and Reneivals of 

 i Machinery. — The report states that, in order to enable 

 [ the British machinery-maker to supply spare parts 

 and renewals, it would be necessary for him to con- 

 tinue the Imperial system in use, side by side with 

 the metric system, for possibly a generation after our 

 official abandonment of the Imperial system, and that 

 he would accordingly be required to work in two 

 systems for that period. 



This objection evidentl)' arises from an unwarrant- 

 able assumption that our adoption oflhe metric system 

 would necessarily involve altered dimensions of 

 machine parts. Such is not the case, because 

 obviously any dimensions now expressed in inches 

 and parts thereof can be readily expressed in milli- 

 metres and parts thereof. It should be remembered 

 that a tolerance of one-hundredth part of a millimetre 

 demands much more accurate work than is usually 

 obtainable in our machine-shops ; so that those oppo- 

 nents of metric measures who claim that metric 

 equivalents of Imperial dimensions can be shown only 

 by employing six figures or so after the decimal point 

 are obviously drawing on their imagination and ap- 

 pealing to the credulity of those whose support the\- 

 seek. 



British manufacturing engineers have for years 

 worked in mils (0001 in.), and the worst the metric 

 system could demand of them. viz. 001 mm., would 

 thus represent a saving of one figure in written dimen- 

 sions. In practice, for small dimensions, two or more 

 figures would generally be saved, because the dimension 

 01 mm. (roughly four mils, or 0004 in.) would be 

 quite fine enough for most of their work. Equivalents 

 expressed even so approximately as the nearest whole 

 millimetre — thus dispensing entirely with the decimal 

 point — could not differ from the original Imperial 

 dimension by more than one-fiftieth part of an inch. 



Furthermore, the passage of an Act requiring all 

 sales to be made in terms of the metric system would 

 not affect the liberty of any person to continue his 

 use of the existing weights and measures for manu- 

 facturing purposes until such time as he himself chose 

 to abandon them. All existing patterns could thus 

 be employed for the full term of their useful lives, and 

 when in the normal course they became worn out or 

 obsolete in design they could be economically replaced 

 by new ones based on the metric system. 



Manufacturers engaging in new industries should, 

 at the outset, base their designs on the metric system, 

 and it is gratifying to note that this has been done, for 

 example, in the case of the British magneto industry, 

 which has been so successfully established in this 

 country since the outbreak of the war. 



The Value of a Universal Language of Quantity. — 

 Regarding the point raised by the Committee that if 

 we now adopted the metric system we should be 

 required to work in two systems for a generation, it 

 may be remarked that, even were this true, it would 

 be much less appalling than our alternative prospect 

 of employing two systems for all time. The fact 

 remains that, whether w^e like it or not, we already 

 find ourselves obliged to use the metric svstem to an 

 ever-increasing extent in scientific work, in manufac- 

 ture, and in export trade ; and the retention of our 

 own Imperial system thus handicaps us by compelling 

 us to employ two systems where one would suffice. 



When we realise that our national existence depends 

 upon our ability to sell British manufactured goods 

 to all nations, i.e. to develop a world-wide trade, it 

 is obvious that Great Britain— more than any other 

 country — would benefit from the establishment of a 

 universal svstem of weights and measures. 



