June 30, 1 88 7 J 



NA TURE 



205 



might be accepted as conclusive, and hence, in determin- 

 ing the weight of a volume of water at any given tempera- 

 ture, the Standards Department have been advised to 

 adopt a mean result from several selected determinations, 

 as those of Despretz, Kopp, and Pierre. 



In many technical works, measurements of gas are 

 erroneously referred to the temperature of 60° F., and not 

 to the legal temperature of 62° F., at which tempera- 

 ture alone the standard foot contains 12 inches ; the 

 standard gallon 10 lbs. weight of water ; and the standard 

 pound 7000 grains. It would appear that an error origin- 

 ally committed in certain hydrometer tables in taking 

 60" F. instead of 62° F., has been followed by many 

 chemical authorities. 



The weight of a cubic foot of ordinary air has been 

 still taken by the Standards Department after the deter- 

 minations of Regnault, as corrected by Moritz, Broch, and 

 Agamemnone. The amount of carbonic acid present in 

 ordinary air has been taken, after the inquiries of Parkes 

 and Angus-Smith, at 6 volumes in every 10,000 volumes 

 of air. If double the quantity, 12 volumes, is present, as 

 is sometimes the case in common rooms, it will make a 

 difference of about o'lS grain in the weight of the cubic 

 foot of air. Ordinary air is still taken, after Regnault, as 

 being two-thirds saturated with moisture. 



In calculating the true weight of any given volume of 

 air or of gas we may, of course, on very rare occasions 

 have to allow for the accelerative effect of the force of 

 gravity at the latitude of the place where the air or gas is 

 weighed, as well as for the height of the place above sea- 

 level. The normal latitude adopted in all such experiments 

 is that of 45^ at sea-level. 



For instance, the weight in grains of a cubic foot of 

 ordinary air (/ = 62° F., B = 30 in.) at London (lat. 

 = 51° 29' 53"), at Edinburgh (lat. = 55° 57' 20"), and at 

 Dublin (lat. = 53° 20' 38"), has been taken as follows :— 



Dry air ^^^ two-thirds Moist air 



■ saturated. saturation = i . 



Gr. Gr. Gr. 



Edinburgh 534 "42 ... 53i'92 ••. S30*68 



Dublin 534-30 ... 531-81 ... 530-56 



London 534-21 ... 53172 ... 53048 



From time to time, on the application of local autho- 

 rities, suggestions are issued by the Board of Trade as to 

 the best modes of testing the weights, measures, and 

 measuring instruments used for commercial purposes. In 

 this country the local inspectors are not bound to follow 

 official instructions as they are in other countries, but are 

 free to carry out their technical work in such a way as the 

 Justices and Town Councils may approve. It is therefore 

 only by the issue of such official suggestions that uni- 

 formity of local practice can be at all reached, and some 

 amount of co-ordination and local effectiveness thereby 

 secured. It is perhaps to be regretted that there is in 

 this country no central authority like the Normal Aichungs 

 Kommission of Germany or Austria to give force and life 

 to the whole local system ; not that we would have the 

 local officers in this country drilled to the dull sameness 

 of official uniformity in the way they are drilled by some 

 Continental Governments, but the absence of a proper 

 scientific training by our local inspectors often leads to 

 complaints from traders and manufacturers. By these 

 official suggestions the Board of Trade endeavour, there- 

 fore, to educate local officers in their technical work and 

 to keep them so far in touch with modern progress. 



The present Report contains a paper on the testing of 

 weighing-machines, which should be of really practical 

 use to the local officers, for it is the first time that any 

 instructions have been published as to the mode of testing 

 such machines. 



Amongst other appendixes to this Report we find 

 papers relating to the well-known model apparatus, de- 

 signed by Sir F. Abel, for testing the flashing-point of 

 petroleum ; abstracts of returns from local officers ; notes 



on the sale of coal by weight and the sale of intoxicants 

 by measure — with reference to which it would appear that 

 there is more petty fraud than ever amongst traders ; and 

 a note on the average current weight of the sovereign. 

 In the latter note reference is made to a number of 

 weighings of gold coin, which have been recently made 

 at the leading Banks in London. The results of these 

 weighings show that most of the gold coinage in circu- 

 lation has really ceased to be legal tender as to weight. 

 Nearly all the coins which were weighed were found to 

 be slightly below the least current weight allowed by 

 the Coinage Act. If the present law, which requires 

 receivers of light gold coins to cut or deface them, 

 were really obeyed, then it would appear from this note 

 that six sovereigns out of every seven ought strictly to be 

 cut or defaced. This seems to be a worse state of things 

 than when Prof. Jevons made his well-known report on 

 the metallic currency of the United Kingdom in 1868. 



THE GERMAN METEOROLOGICAL OFFICE. 



A HISTORY of the Royal Prussian Meteorological 

 -^*- Institute from the time of its establishment in 1847 

 until its re-organisation in 1885, by Dr. G. Hellmann, has 

 just been published in the year-book of the Institution, 

 " Ergebnisse der Meteorologischen Beobachtungen im 

 Jahre 1885 " (Berlin, 1887, 246 pages, large 4to, with plates). 

 Dr. Hellmann is well-known to students of meteorology by 

 many very valuable articles, and especially by his laborious 

 compilation of a " Repertorium der Deutschen Meteoro- 

 logie," containing a list of the articles, inventions, and 

 observations in the domain of Meteorology and Terrestrial 

 Magnetism in Germany from the earliest times down to the 

 year 1881 (Leipzig, 1883, 995 pages, large 8vo). The king- 

 dom of Prussia was relatively late in organising a regular 

 system of observations, Baden and Bavaria in Southern 

 Germany havingestablished well-appointed services before 

 the end of the last century ; and Wiirtemberg followed 

 with its system in 182 1-2. The want of trustworthy data 

 for Northern Germany was much felt by Baron A. von 

 Humboldt at the time of the construction of his first 

 isothermal charts in 1817, and the establishment of the 

 service in Prussia was due to the urgent representations 

 which he made to the present Emperor. In 1847 a system 

 of 25 -30 stations was established under Dr. Mahlmann,and 

 observations were taken at the hours of 6, 2, and 10 ; these 

 hours have been generally adhered to both in Germany 

 and Austria down to the present time. Before commenc- 

 ing operations, all the stations were duly inspected, and 

 suitable observers selected, mostly from teachers in the 

 upper schools. While neither instruments nor remunera- 

 tion are provided for such observers in this country, in the 

 Prussian system an annual allowance, varying from about 

 £7 \os. upwards, according to circumstances, is made to 

 manyof the observers, together with an outfit of instruments. 

 The result of these arrangements has been that probably 

 in no other system upon the globe have so many useful 

 works been published by the various observers, upon 

 whom generally devolved the task of working up their own 

 observations. Dr. Mahlmann having died suddenly on 

 one of his tours of inspection, his work was taken up in 

 April 1849 by the late eminent Prof. H. W. Dove, of the 

 University of Berlin, and his first care was to revise the 

 observations hitherto taken and to publish them in a first 

 Report of the Observations taken in 1848-9. The pub- 

 lication of this Report induced several other states to join 

 the Prussian system, many of the observers now taking 

 up the work without remuneration, and this active co- 

 operation enabled Dove to publish for 1855, and for 

 subsequent years, a summary of observations for each 

 month of the year for Northern Germany, and in 1858 a 

 first sketch of the climatological conditions based upon 

 ten years' observations. Prior to this publication these 



