458 



NATURE 



[October 5, ign 



from near 



Finally, A. Wade describes Silurian rocks 

 Welshpool, including some of igneous origin. 



A map by the Edinburgh Geographical Institute, show- 

 ing the density of population in Scotland as given by 

 the census of 1911, appears in The Scottish Geographical 

 Magazine lor September. The method of Bosse is 

 employed in calculating the density values, in which all 

 uninhabited country and all urban districts and towns of 

 10,000 inhabitants and upwards are left out of account. 

 Comparing it with the map setting forth the results of 

 the 1901 census, the areas of densest population show a 

 marked increase in spite of the reduced rate of increase 

 of the population as a whole. The south shore of Moray 

 Firth and the neighbourhood of Wick are also areas where 

 population density has increased. These last two areas 

 are connected with the fishing industry, which has 

 improved of late, while the mining and manufacturing 

 industries of the lowland region has drawn people to it. 



Tun valuable rainfall reports for the German pro- 

 tectorates of (1) Togoland (West Africa) for 1910, and 

 (2) South-West Africa, for two years ended June, 1910, 

 published by Baron v. Danckelman in Mitteilungen aus den 

 Deutsdicn Schutzgebieten (vol. xxiv., part ii., ion), show 

 that in the first case the amount of rainfall was very 

 favourable ; in the coastal and central districts it was a 

 record year, and at most of the stations the wettest since 

 the commencement of regular observations in 1901. In the 

 second case the rainfall for the fiscal year ended June, 

 1909, everywhere exceeded the average of the last ten 

 years. The excessive amount caused an undue develop- 

 ment of injurious insects, malaria, and sickness among 

 cattle. In 1909-10 the amount was generally satisfactory, 

 but not nearly so abundant as in the previous year. Rain 

 is mostly accompanied by thunderstorms ; in places 

 thunderstorms frequently occur without rain. 



A detailed summary of the meteorological observations 

 made at the municipal observatory of the city of Bremen 

 has just been published under the title " Beitrage zur 

 Klimabeurteilung Bremens." The work is in two parts. 

 In the first section the diurnal variations of the various 

 meteorological elements are set out, , both for the seasons 

 and for the whole year, but the harmonic coefficients have 

 not been determined. The second section concerns itself 

 with monthly means and extremes, and for purposes of 

 comparison corresponding values are given for Berlin and 

 Frankfurt. The moderating influence of the ocean on the 

 climate of the seaport is very strikingly brought out by 

 this juxtaposition of figures, and the full meteorological 

 statistics which are given for all three towns form a very 

 useful book of reference. The work has been compiled by 

 Prof. W. Grosse, the director of the observatory. 



We have received copies of the valuable meteorological 

 charts of the great oceans issued by the U.S. Weather 

 Bureau for October. The reverse sides of those for the 

 North Atlantic and North Pacific Oceans contain interest- 

 ing papers by Prof. W. J. Humphreys (1) on the origin 

 of the permanent ocean " highs," and (2) the Aleutian 

 and Icelandic " lows," illustrated by maps. There is a 

 close connection between the positions and intensities of 

 these areas and the weather of adjacent continents ; they 

 are the maxima and minima, with closed isobars, in the 

 belts of high and low pressure, or so-called centres of 

 atmospheric action. The subject of the importance of 

 observations in these belts was brought before the Inter- 

 national Meteorological Committee at the St. Peters- 

 burg meeting in 1S99, and at the conference at Inns- 

 bruck, in 1905, a resolution of the Solar Commission 

 NO. 2 I SB, VOL. 87] 



advocating the establishment of permanent stations in 

 the regions in question was unanimously- adopted. 

 Few attempts have been made to explain ' the origin 

 of the maxima and minima ; the author refers to the 

 hypotheses put forward by Ferrel and Angot, and has 

 supplemented them by one of his own. He concludes, 

 inter alia, that a maximum ocean " high " must be at 

 that place where the mechanical and thermal causes com- 

 bine to produce the greatest result, i.e. a little to the west 

 of the intersection of the coldest portion of an ocean 

 current with a high-pressure belt. 



From the observations of Eve at Montreal, Ashman at 

 Chicago, and Satterly at Cambridge, it has been concluded 

 that in each cubic metre of air near the ground there is 

 an amount of radium emanation which would be in 

 equilibrium with Sox 10- 12 grams of radium. This con- 

 clusion has been confirmed by observations made at Tokyo 

 by Messrs. Kinoshita, Nishikawa, and Ono, which are 

 described in the June number of the Proceedings of the 

 Tokyo Mathematico-Physical Society. The amount of 

 emanation decreases with distance from the ground, but if 

 a homogeneous layer only 5 kilometres thick be taken as 

 the equivalent of the whole atmosphere, over each sq 

 metre, there is an amount of emanation which would be 

 in equilibrium with 4X10- 7 grams of radium. Half of 

 this breaks up in 3-7 days, and the question arises, how is 

 the supply to be kept up? If it is derived, as it has been 

 thought to be, from the strongly active air which exists 

 in the pores of the soil, it must be possible to show by 

 measurement that a large amount of emanation is exhaled 

 from a square metre of soil. This has just been done by 

 Prof. Joly and Mr. Smyth, who describe their observations 

 in the August number of the Proceedings of the Royal 

 Dublin Society. They find that near Dublin the amount 

 exhaled often exceeds the 2-9x10-' grams per square metre 

 per hour necessary to maintain the atmospheric emanation. 



With the year 1910 the Ergebnisse der magnetischm 

 Beobachtungen of the Royal Observatory of Wilhelms- 

 haven commences a new series, edited by Prof. Bidling- 

 maier, the assistant director. The volume extends to forty- 

 five pages, and possesses two charts. It contains an account 

 of the absolute and self-recording instruments. At present 

 the latter consist of declination (D) and horizontal force (H) 

 magnetographs of the Kew pattern by Adie, but a vertical 

 force instrument seems under construction. The methods of 

 observation and reduction, and the base values of the curves, 

 are treated in great detail. One reason for this doubtless 

 is that, following the example of Potsdam, mean values 

 are assigned to every day of the year, which go to 17 in 

 H and to o-i' in D. Again, following Potsdam, the hourly 

 values represent mean ordinates from sixty minutes 

 centring, not at exact hours of the day, but at half hours. 

 Mean diurnal inequalities are given for individual months, 

 going to 001' in D and to o-i 7 in H and in the north and 

 east components. Corresponding values are also given in 

 the case of the components for the Fourier 24, 12, 8, and 

 6-hour terms. The last two pages give vector diagrams 

 for the diurnal inequality for individual months. In the 

 diagrams and diurnal inequalities use is made of all days, 

 whether quiet or disturbed, which probably explains the 

 rather striking irregularities in the diagrams. While the 

 influence of Potsdam example is manifest in the more I 

 normal parts of the volume, the treatment of disturbances 

 affords scope for the ventilation of Dr. Bidlingmaier's own 

 methods ol treatment, 



1 he experimental study of vortex rings has in the past 

 been qualitative rather than quantitative ; but, according to I 



