384 



NATURE 



\Augtist 25, 188] 



among those in the rear of civilisation. However this 

 may be, M. Pitre de Lisle has done good service to 

 archaeology in publishing his monograph upon this 

 peculiar form of stone implement or weapon. 



INTERNATIONAL BUREAU OF WEIGHTS 

 AND MEASURES 



UNDER the authority of the Comitd International, 

 representing several countries of Europe, the 

 United States, and South America, there has been 

 recently published, by Gauthier-Villars of Paris, an 

 important volume of Memoirs by Dr. Broch (Directeur 

 du Bureau), and Drs. Pernet, Renff-Benoit, and Marek 

 (Adjoints du Bureau), on the following subjects relating 

 to the determination of units of measure and weight. 



As the intensity of weight varies with geographical 

 position and height above level of the sea, the Comitt? 

 give in their first memoir tables of the ratio of the 

 acceleration of weight at the level of the sea, for different 

 latitudes, to its acceleration at latitude 45° (Paris), to 

 which latitude the Comite recommend that all weighings 

 might be referred. The tables are based on the formula 

 of Laplace, the coefficients of which are corrected by 

 Broch in accordance with recent deductions as to the 

 figure of the earth. In the second memoir, which relates 

 to the tension of aqueous vapour, certain corrections of 

 hitherto accepted results are also indicated, particularly the 

 errors of calculation in Regnault's tables as shown by 

 MoritE, and new tables are given for tensions at all 

 absolute barometer heights for normal degrees from 

 - 30° to + 101° C. 



With reference to the fi.xed points of mercurial thermo- 

 meters, the Coraiti^ adopted the proposition that the point 

 0° of the Centigrade thermometer should be fixed at the 

 pressure of 760 mm., when determined in 45° latitude, 

 and at the mean level of the sea. Also at the Congress 

 of Meteorologists at Rome in 1879 there was adopted 

 the proposition of Dr. Pernet, to fix the boiling point of 

 water, 100° C, under the above pressure, so as to render 

 strictly comparable the temperatures observed at different 

 places. Degrees of temperature between these points 

 are termed normal-degrees. 



Tables are also given, by which may be calculated the 

 weight of a litre of pure air in different latitudes and at 

 different altitudes. In London (lat. =51° 30', alt. =67 

 metres) the weight is r293S grammes. The Comit^ have 

 adopted the term litre for expressing the volume of a 

 kilogram of pure water, instead of the term cubic-deci- 

 metre. 



In a report by M. Herr on the Austrian unit of weight 

 (Vienna, 1870), the volume of pure water at various tem- 

 peratures is stated from the means of observations by 

 Muncke, Stampfer, Kopp, and Pierre, the maximum 

 density of water being taken at 3''92796 C. By this 

 formula there have been calculated, under the directions 

 of the Comite, tables of the volume and specific weight 

 of water from o' to 30^ C. 



One of the principal works executed during 187S-9 was 

 the comparisons of the standard kilograms at Vienna, 

 Paris, and London. An elaborate report on these com- 

 parisons is given by M. Marek, who, by improved 

 methods and instruments, has obtained great accuracy. 

 The probable error of his weighings is about o'oo2 mgr., 

 or I -500,000,000th part of the whole weight. The results 

 also show that the material of which the standards are 

 made, 90 per cent, of platinum and 10 per cent, of iridium, 

 is of all known bodies the least affected by time or atmo- 

 spheric changes. 



In a paper on Fizeau's apparatus for determining the 

 rates of expansions of bodies by heat, by means of an 

 optical method founded on the phenomena of interference, 

 Dr. Benoit gives the results of his own experiences with 

 a similar apparatus. The results show the wonderful deli- 



cacy of Fizeau's dilatometer, as the expansions by heat 

 of small specimens of platinum are shown in a manner 

 incontestable to millionths of a millimetre (o 00000004 

 inch). 



An interesting account of the establishment and objects 

 of the Bureau is given in a preface to this volume by the 

 Secretary to the Comitd, Dr. Ad. Hirsch ; and it is hoped 

 that the efforts made by the Comite to bring about 

 international agreement on the scientific points above 

 referred to will commend themselves to all engaged in 

 accurate work. H. J. Chaney 



A MODEL PUBLIC LIBRARY 

 "ENGLISHMEN are fond of descanting upon the evils 

 ■'--' of too much centralisation, which they see displayed 

 in some foreign systems of government, urging the amount 

 of red tape rendered almost necessary, its inflexibihty, 

 and lack of adaptation to the infinitely-varying circum- 

 stances of different communities. But, on the other hand, 

 the extravagant cost of working every undertaking by a 

 separate organisation, especially in a community not large 

 enough to make such undertakings great matters, must 

 come forcibly home to many of those who are naturally 

 selected to work upon several. 



There has lately come under our notice an admirable 

 case of a public library avoiding this waste, securing all 

 the energy of private zeal, and at the same time increasing 

 the working power of it by becoming, as a public library 

 should become, the centre of all secondary education 

 and the parent stem of many and various branches. If 

 any of the smaller towns of England feel that a free 

 library would not in their case stand by itself on accoimt 

 of small income, we commend this to their notice as a 

 specimen of the advantages of co-operation. 



Watford has a population of about 10,000, and the 

 penny rate on last year's gross rental of 34,589/. brought 

 in 144/. 2s. Yet this small amount has developed round 

 it an expenditure of 700/. a year, equal to five times the 

 largest rate collected, besides a large outlay on buildings 

 at the beginning, costing some 3000/. subscribed, in addi- 

 tion to the gift of the land. Ten distinct sections are worked 

 in connection with it. The accounts of each are shown in a 

 separate balance-sheet each year, and the agenda paper, 

 with notice of committee-meetings, shows how methodi- 

 cally the work of each section is carried out and over- 

 hauled. 



Section A, the Library proper, contains about 7000 

 volumes ; a payment of three shillings a year, or f ourpence 

 a month, is required for taking books home to read ; the 

 yearly issues accordingly amount to about 12,000. The 

 only_//£v part of the library, the reading-room, shows a 

 something similar use of books ; it is patronised chiefly 

 by young men in the winter time, under the arrangements 

 of Section D. The small subscription enables the book 

 committee to spend about 50/. a year in new books ; 

 magazines and periodicals being supplied by a separate 

 club, connected, of course, with the institution. We 

 should be glad to see the troublesome and irksome system 

 of guarantors dropped. Towns whic'a have freed them- 

 selves from the labour and annoyance they entail, though 

 containing far larger proportions of the "great unknown " 

 than can a place of the size of Watford, have found no 

 evil result. The subscription also, though small, seems 

 to render it less necessary here. 



Section B is the School of Science and Art, the latter 

 division showing clearly that the public library at Wat- 

 ford by no means attends to the wants of the industrial 

 classes only, for non-Government pupils may pay six 

 guineas a year for drawing only. For the benefit of the 

 evening classes, at which non-Government pupils pay a 

 guinea and a half for the year's instruction, and Govern- 

 ment students (whose income, that is, or parents' income,, 

 does not exceed 200/. a year) half that, " the subjects are 



