August 14, 1913 



NATURE 



tv 



well-known names as Vines, Meldrum, Algu6, and 

 ffihers; to the variation of the storms with time and 

 place ; to their tracks and rates of progression of the 

 Srtices; the whole of which will repay careful 

 perusal. Actual reference is not made to the article 

 on the same subject in the valuable "Barometer 

 Manual " issued by the London Meteorological Office, 

 which epitomises the results of observations and ex- 

 perience extending over many years. A glance at this 

 work, in conjunction with Mr. Hurd's compilation, 

 explains how in either hemisphere the wind travels 

 round the eye Ionic centre in a direction contrary to 

 the apparent diurnal course of the sun, the westerly 

 wind being therefore always found in the portion of 

 the whirl nearest to the equator. The average rati 

 of progression ((irrespective of the wind-force in the 

 whirl) varies from about 300 miles a day in the West 

 Indies to from fifty to 200 miles in the southern 

 Indian Ocean. Fassig found thai in the West Indies 

 tie' average daily rate further increased after the 

 recurve of the 



The Ergebnisse der magnetischen Beobachtungen 

 of the Royal Observatorj of Wilhelmshaven for the 

 year 1911, in addition to valuable information about 

 magnetic diurnal and secular variation at Wilhelms- 

 haven, contains an elaborate discussion by Prof. 

 Bidlingmaier of what he calls "die erdmagnetische 

 Aktivitat." By "activity" he means a more exact 

 numerical measure of the energy of magnetic forces 

 than is afforded by the present international scale, 

 which assigns o to a quiet, 1 to a moderately dis- 

 turbed, and 2 to a highly disturbed day. Prof. Bid- 

 lingmaier's introductory remarks on the theoretical 

 side are of extreme generality, but practically he 

 assumes the "activity" for a given interval of time 

 in a magnetic element to be proportional to the mean 

 .square of the differences of its values taken at a 

 large, theoretically infinite, number of equidistant 

 times throughout the interval from the mean value 

 during the interval. By summing the "activities" 

 for three rectangular components one would have a 

 measure of the total "activity." The interval of time 

 may be the hour, the day, or the year. In the first 

 case, in practice, Prof. Bidlingmaier seems to approve 

 of values at six-minute intervals. The labour 

 involved in arriving at hourly "activities" throughout 

 the whole year being very great, an attempt was 

 made to see whether the "activity" in this case could 

 be expressed as a definite function of the range. 

 Hours having the same range were collected in 

 groups, and the corresponding mean measured "activi- 

 ties" were plotted as ordinates of a curve of which 

 the abscissa? were the ranges. A regular curve was 

 thence derived, somewhat resembling part of an hyper- 

 bola. The work merits the attention of all interested 

 in magnetic disturbance. 



Engineering for August 8 contains an illustrated 

 account of experiments on the distribution of wind 

 velocity in the space surrounding a circular rod in a 

 uniform current of air. These experiments were con- 

 ducted at East London College by Prof. J. T. Morris. 

 The wind velocity was measured by electrical appa- 

 ratus. Electrically heated wires were attached to the 

 NO. 2285, VOL. 91] 



circular rod, and the cooling of these wires by the 

 air current was used as a measure of the wind velo- 

 city. The method has been described already by Prof. 

 Morris at the Dundee meeting of the British Asso- 

 ciation, and at the recent soiree of the Royal Societ] . 

 The present article gives complete sets of curves show- 

 ing the wind velocity at different distances from the 

 rod for various speeds of main air current, together 

 with velocity-contour lines for currents of fifteen and 

 five miles per hour. The " shadow " of the rod is 

 brought out clearly by these graphs, and extends much 

 further at low than at high velocity. Judging from 

 the results, the electrical method of measuring air 

 velocities seems to possess considerable advantages in 

 the field of experimental aerodynamics. 



The foreign commerce and navigation of the United 

 States for the year ending June 30, 1912, is dealt with 

 in a volume prepared by Mr. O. P. Austin, and pub- 

 lished at Washington by the Department of Commerce 

 and Labour in the United States. The bulky volume 

 of 1342 pages is concerned almost wholly with statis- 

 tics, and provides detailed information of every de- 

 partment of the trade of the United States. In the 

 fiscal year 1912 the exports of manufactures from the 

 States were larger than in any earlier year in the 

 record of American commerce, and imports of manu- 

 facturers' materials also showed larger totals than 

 in any earlier year except 1910. This increasing share 

 which manufactures form in American exports, and 

 manufacturers' materials form in the imports, is 

 chiefly a development of recent years. Manufactures 

 are supplanting foodstuffs as a leading factor in the 

 export trade of the United States. While the value 

 of foodstuffs exported increased from 1885 to 1900, 

 it has actually declined since that date. The per- 

 centage which foodstuffs formed of the total exports 

 has declined steadily since 1S80; on the other hand, 

 the percentage of manufactures has as steadily in- 

 creased. 



OUR ASTRONOMICAL COLUMN. 



Radial Velocity of 915 Stars. — Prof. Campbell 

 publishes in Lick Observatory Bulletin, No. 229, a 

 further valuable contribution to the radial velocities 

 of stars secured with the Mills spectrographs attached 

 to the 36-in. refractor at Mount Hamilton, and with 

 the instruments of the D. O. Mills Expedition at 

 Santiago, Chile. Prof. Campbell states that the re- 

 sults for those brighter stars of classes F, G, K, and 

 M, of which the radial velocities appear to 

 be substantially constant, or the approximate systemic 

 velocities may be estimated, including proper- 

 motion and other auxiliary data, relating to nearly 900 

 stars, have existed in manuscript form ready for the 

 printer for more than a year. It was proposed to 

 issue them in the form as previously published for 

 the stars classes B and A, but want of funds made 

 such a scheme impossible. Even now the necessary 

 means are not forthcoming, so, to avoid further delay, 

 he publishes them in the briefest form in the present 

 bulletin. 



All available results for stars of these spectral classes 

 have been included, whether the observations of the 

 same stars have been published or not in former lists ; 

 there are also included velocities for a few stars of 

 classes B and A. Results for a few stars obtained at 



