April 30, 1908J 



NA TURE 



611 



could ix'ad, move about to some extent, and sleep for 

 prescribed periods. But his every action was watched 

 through a window and recorded. There were no 

 meals to help him pass the time, and the principal 

 occupation of the prisoner was counting his pulse, and 

 respiration, and carefully collecting his excreta at 

 frequent intervals. These were subsequently analysed, 

 and their various constituents estimated. .\t the same 

 time, the amount of oxygen used, of carbonic acid 

 and water exhaled, of heat produced, and other fac- 

 tors too numerous even to catalogue, were all deter- 

 mined and recorded. One striking outcome of the 

 work was that in the diaries reproduced com- 

 paratively little suffering apart from ennui was 

 recorded. The same has been previously stated by 

 professional fasters ; we can therefore hardly doubt 

 that in animals also the actual suffering- has been 

 small when they have been subjected to the with- 

 drawal of solid food for a few days. The book is to 

 be commended ;o all interested in physiological work, 

 and especially to those engaged in a study of nutrition. 



' W. D. H. 



RECEXT PROGRESS OF THE METRIC 

 SYSTEM.'^ 



AN important report by Dr. Guillaume, presented 

 at the meeting of the General Conference of 

 Weights and Measures at Paris in October last, has 

 recentlv reached us. Dr. Guillaume commences his 

 report with an interesting account of some recent 

 investigations which have been made at the Inter- 

 national Bureau of Weights and Measures with re- 

 spect to the permanency and invariability of the iridio- 

 platinum standards of the metre and the kilogram, 

 which were distributed in 1889 to the several States 

 participating in the Metric Convention of May, 1875. 

 The result of these researches is very satisfactory, and 

 savs much for the high standard of accuracy main- 

 tained in the metrological determinations of the 

 bureau. Among other investigations which have 

 been undertaken at the bureau since the previous 

 meeting of the general conference in iqoi, attention 

 is directed to tfie work of MM. Benoit, Fabry and 

 Perot in connection with the interferential measure- 

 ment of light waves. The results obtained confirm in 

 a remarkable manner the value found by Michelson 

 and Benoit in 1892-3 for the length of the metre in 

 terms of the wave-length (x) of the red radiation of 

 incandescent cadmium, in dry air at 760 mm. pressure, 

 and at the temperature of 15° on the normal hydrogen 

 scale. The new value, viz. : — 



Metre= 1,553,164-13 A, 



leads to the following equivalent for the length of the 

 vard, viz. ; — 



Vard = 1,420,212-04 \. 



These values differ from the earlier determination of 

 Michelson and Benoit by less than one part in 

 10,000,000, from which it may be inferred that the 

 interferential method of linear measurement can lay 

 claim to a degree of accuracy far surpassing that 

 attainable with the best micrometer microscopes. 



.\nother important research, which has occupied the 

 bureau for many years past and has now reached its 

 final stage, is the determination of the weight of a 

 given volume of pure water at its maximum density. 

 From this investigation, w-hich has been conducted 

 principally by MM. Chappuis and Guillaume, the 

 weight III vacuo of a cubic decimetre of water at 

 4° C. has been ascertained to be 0*999972 kilogram. 



1 " Les rtfcents Progrts du Systeme m^trique." By Ch.-Ed. Guillaume. 

 Pp. 94. (Paris : Gauthjer-Villars, 1907.) 



NO. 2009, VOL. 77] 



-As the weight of a gallon of water at 62° F., weighed 

 against brass weigfits in air at the same temperature 

 and with the barometer at 30 inches, is defined as 

 being lolb. avoirdupois, the following value for the 

 cubic contents of the gallon may be readily deduced 

 from the above result, viz. : — 



Gallon = 277 '420 cubic inches. 



It follows that, under the same conditions of tem- 

 perature and pressure as in the gallon equivalent, 



I cubic foot of water = 62-288 lb., and 

 I cubic inch ,, =252-325 grains. 



Further investigations on the subject are in pro- 

 gress at the bureau, but it is unlikely that the final 

 results will be found to difier appreciably from those 

 given above. The values at present legalised in this 

 country, which are based on determinations made by 

 Kater in 182 1, are far from accurate, but legislators 

 aro naturally chary of prescribing new relations 

 between physical magnitudes before science has said 

 lier last word on the subject. 



With respect to thermometry, researches undertaken 

 at the bureau during the period covered by this report 

 indicate that the normal scale of temperature adopted 

 by the international committee in 18S7 is practically 

 in perfect agreement with the absolute thermometric 

 scale. The corrections previously determined for re- 

 ducing the readings of mercury thermometers to the 

 latter scale are found to hold good even for instru- 

 ments of the most recent construction. Formerly 

 Tonnelot thermometers were employed at the bureau 

 in metrological determinations, and thermometers of 

 this type were supplied with the various national 

 prototypes which were distributed in 1889. Of recent 

 years preference has been given to instruments con- 

 structed by Baudin, w-hich are subjected to a pre- 

 liminary course of artificial heating in the vapour of 

 sulphur. It has been found at the bureau that ther- 

 mometers treated by this process acquire almost 

 perfect stability. 



Dr. Guillaume devotes one chapter of his report 

 to recent legislation in different countries with respect 

 to the metric system of weights and measures. 

 During the last few years the metric prototypes of 

 the bureau have been legally recognised in France 

 and Roumania, and the laws of these countries have 

 been brought into harmony w-ith the present con- 

 ditions of metrology. In Hungary a law was recently 

 passed defining the units of force, pressure, and 

 density in terms of the metric sj'Stem. The legislature 

 of Denmark has provided for the adoption of the 

 system in that country by the year 1910. The system 

 has also been made obligatory in the Portuguese 

 colonies. On the other hand, Dr. Guillaume does not 

 find much progress to record in Great Britain and its 

 colonies or in the United States, so far as legislation 

 is concerned. Canada has, however, w-ith the ac- 

 quiescence of the British Government, formally joined 

 the Metric Convention on the footing of a separate 

 State, and in New Zealand an ordinance has been 

 passed prescribing the exclusive use of the sj'stem 

 after an indefinite date. 



A resolution of the general conference urging upon 

 the various contracting States the formal adoption of 

 a metric carat of 200 milligrams for use in the sale of 

 diamonds and precious stones has been brought by 

 the several Governments under the notice of the in- 

 dustry concerned. At present it is not possible to 

 anticipate what response will be made by the trade. 

 In this country the carat is not legally recognised, 

 but as a customary weight its value is generally 

 accepted as being 3'i683 grains, or 1513 carats to the 



