June it, 1903] 



NATURE 



U9 



The counting' of the Chart plates has been continued 

 during the year, and completed between Dec. 64° and Dec. 

 70°. A paper on the statistics of the stars between 65° and 

 70° N. Dec. was communicated to the Royal Astronomical 

 Society in January, and printed in the Monthly Notices. 



The 28-inch refractor has been used throughout the year 

 for micrometric measurements of double stars. The total 

 number of double stars measured during the year is 381 ; 

 of these 192 have components less than 1*0 apart, and 105 

 less than o''-5. 



Series of measures have been obtained of k Pegasi, 

 S Equulei, 70 Ophiuchi, and ( Herculis. Capella has been 

 examined at every favourable opportunity, and observations 

 of the position angle of the elongated image have been 

 secured on eight occasions. 



Solar Activity. — Shortly after the date of the last report 

 a long period of almost complete solar quiescence set in ; 

 from 1902 June 5 to September 17 inclusive, a period of 

 105 days, the mean daily spotted area was less than a 

 single unit (one millionth of the sun's visible hemisphere). 

 An active period set in on September 18 and lasted until 

 November 28, 72 days, the mean daily area being 164 

 niillionths. The rest of the year 1902 was very quiet, the 

 remaining 34 days showing a mean daily area of only 3. 

 In the present year the sun has been much more active, and 

 has been free from spots on only 14 days since January i, 

 as compared with about 100 in the same period of last year. 

 The first of a fine series of spot-groups appeared on the 

 east limb on 1903 March 21, and a succession of new groups 

 has followed almost without intermission up to the date 

 of this report. There can be no doubt, therefore, that the 

 solar activity is very decidedly upon the increase. 



Tables and diagrams showing the distribution of sun- 

 spots in latitude and the areas of sun-spots and faculae com- 

 pared with magnetic diurnal ranges for the 29 years 1874 

 to 1902 have been prepared, and will be published in the 

 .Monthly Notices R.A.S. for May. 



Magnetic Observations. — The principal results for the 

 magnetic elements for 1902 are as follows : — 



Mean declination 16° 22' 8 West. 



/ 4 0134 (in British units). 

 ■" 1 I '8505 (in Metric units). 



Mean dip (with 3-inch needles) 67° 3' 25". 



Meteorological Observations. — The mean temperature for 

 the year 1902 was 49°!, or o°-4 below the average for the 

 50 years 1841-90. 



The rainfall for the year ending 1903 April 30 was 2368 

 inches, being 086 inch less than the average of 50 years. 

 The number of rainy days was 172. The rainfall has been 

 less than the average for each of the eight years from 1895 

 to iqo2 inclusive, the total deficiency for the eight years 

 ending 1902 December 31 amounting" to 28-91 inches. For 

 the four months 1903 January-April there has been an 

 e.vcess of 095 inch. 



THEORY OF CYCLONES AND ANTICYCLONES. 

 pROF. F. H. BIGELOW contributes to the U.S. 

 .Monthly Weather Review for February a paper on 

 the mechanism of counter-currents of different tempera- 

 tures in cyclones and anticyclones. An outline theory of 

 the structure of cyclones and anticvclones was described 

 in the report of the Chief of the Weather Bureau for 1898- 

 1899 (vol. ii). It was evident, however, that a more com- 

 plete insight into the mechanism of motions in a fluid such 

 as air under atmospheric conditions would be afforded by 

 the construction of systems of isobars on at least three 

 planes having different altitudes. For this purpose, the 

 sea-level and the levels of 3500 and 10,000 feet were selected, 

 and since December, 1902, daily reduced pressures for these 

 planes have been received from the regular observing 

 stations of the United States and Canada, and charts have 

 been constructed for them. The approximate gradients 

 needed for a preliminary consideration of the subject have 

 thus been obtained, and the general results of the investi- 

 gation are stated by Prof. Bigelow as follows : — 



(i) The cyclone is not formed from the energy of the 

 latent heat of condensation, however much this mav 

 strengthen its intensity : it is not an eddy in the eastward 



Mean horizontal force 



NO. 1754, VOL. 68] 



drift ; but it is caused by the counterflow and overflow of 

 currents of different temperatures. Ferrel's canal theory 

 of the general circulation is not sustained by the observ- 

 ations, nor is his theory of local cyclones and anticyclones 

 tenable. There are difficulties with regard to the German 

 vortex theory, but this is nearer the truth than the Ferrel 

 vortex. The structure in nature is actually more complex 

 than has been admitted in these theoretical discussions, 

 but it doubtless can be worked out successfully along the 

 lines herein indicated. (2) Regarding the relation of the 

 upper level isobars to practical forecasting, it is noted as 

 the result of the examination of charts that (a) the direction 

 of the advance of the centre of the low pressure is controlled 

 by the upper strata, and its track for the following twenty- 

 four hours is usually indicated by the position of the 10,000- 

 foot level isobars ; (h) the velocity of the daily motion is 

 also dependent upon and is shown by the density of these 

 high level isobars ; (c) the penetrating power of the cyclone 

 is safely inferred from an inspection of the three maps of 

 isobars of the same date ; (d) there is decided evidence that 

 areas of precipitation occur where the 3500-foot isobars and 

 the 10,000-foot isobars cross each other at an angle in the 

 neighbourhood of 90° ; (e) there have been several cases in 

 which the formation of a new cyclone has been first dis- 

 tinctly shown on the upper system of isobars before pene- 

 trating to the surface or making itself evident at the sea 

 level. (3) It is expected that by completing our discussion 

 of the temperature gradients between the surface and the 

 higher levels we shall be able to secure daily isotherms as 

 well as daily isobars on the upper planes, and this will 

 tend to strengthen any further examination of these im- 

 portant problems. A suitable report will be prepared in 

 which the data now coming into our possession will be 

 subjected to a mathematical analysis and discussion. 



ATMOSPHERIC VARIATIONS. 

 Tj* ROM the results of recent researches solar prominences 

 ■*■ seem to be playing a most important part, not only 

 in the mechanism of the solar atmosphere, but in the 

 variations of our own. Any investigation, therefore, that 

 gives us new ideas or corroborates the old is most useful 

 and valuable. In a previous number of this Journal (vol. 

 Ixvii. p. 569, April) an account was given of the results 

 obtained from a research on the distribution of solar 

 prominences as regards latitude. The prominence circula- 

 tion thus disclosed that there was practically a law at 

 work which the centres of prominence action followed, and 

 this law, deduced from observations extending over the 

 longest period available (1872-1901), was found to be in 

 good agreement with that first suggested by Prof. Ricco 

 in 1891 {.Mem. d. Soc. degli Spettr., vol.'xx. p. 135). 

 Prof. Bigelow has also been studying the question of 

 prominence, facula and spot circulation, and in a recent 

 number of the Monthly Weather Review (vol. xxxi. No. i, 

 p. 9) has stated his results. The method he adopted was 

 somewhat different from the one first mentioned above, for 

 the prominence circulation determined by him has been de- 

 duced by finding the mean variation of the prominence dis- 

 tribution resulting from coupling up together the values for 

 those years which he considers are similar in relation to 

 the eleven-year sun-spot cycle. Anyone familiar with this 

 cycle knows the difficulty this involves, because it is only 

 the mean length of the sun-spot period that is eleven years. 

 Further, the epochs of maxima do not follow those of the 

 minima at constant intervals, but vary from a little more 

 than three to five years. In spite, however, of these probable 

 sources of error. Prof. Bigelow deduces a circulation not 

 very different from the one mentioned above, so that all 

 the three computations and deductions show that there is 

 a very definite movement in latitude and change in per- 

 centage frequency of occurrence from year to year. 



.\ most interesting and important contribution, by Prof. 

 T. H. Davis, to our knowledge of the fluctuation of the 

 annual wind resultants, and indirectly to our knowledge of 

 the movements of cyclones and anticyclones, appeared in one 

 of the recent numbers of the Monthly Weather Review (vol. 

 XXX. No. II, p. 519), The investigation was restricted 

 chiefly to stations included in the meteorological services of 

 the United .States and Canada, and the period discussed 

 was the ten years 1891-1900. The results of the research 



