15 



outward of sticcuMive low pressure systems orr the Southern Ocean, relatively warm air U coimuntly 

 lieing drawn from lower latitude* in front of central area* of depression, which, after parting with heat in 

 the frigid cone and Iwing still further . Inllr.l l.y i|,,. mixing of air of polar origin, leave the Antarctic M a 

 ("lil wind. 



Tin.* exposition of surface wind . in ul iti.m in high latitudes, which is bated on a cloM examination of 

 the nwulu of observation* represented on the daily charta, wai offered by the writer in the memoir on tin- 

 Climatology of South Victoria Liml in 1'art I. f this work. The propoiition hat lince been elaborated 

 .iii.l extended to equatorial regions hy Dr. W. J. LOCKYER,* who suggesu that the warm air currenU 

 in ul:tiiii: in front of the baric minima of eattward moving depressions are of equatorial origin, and that 

 hey have traversed the southern and western segments of their circuit they rejoin the westerly air 

 current, and so return by the trade wind circulation to the equator on the eastern side of anticyclones. 



This, as the writer understands it, is in effect the suggestion put forward, and it is a proposition with 

 whirh, in the main, ho is in accord. 



ANTICYCLONES OF THE SUB-TROPICAI. BELT. 



In regard to this subject Dr. LUCKY Kit, in the work already quoted, favours the views held by the late 

 M II i r'.RA, ( M <!., in regard to these ocean anticyclones and the high-pressure belt. He 



believes that in latitudes north of the cone of travelling depressions in the Southern Ocean a train of 

 .mi : v- !MCS moves eastward, following one another in quick succession, ami that in charting the mean 

 results of barometer readings recorded in those latitudes the effect is produced on chart* relating to average 

 pressure of permanent areas of maximum barometer within a permanent belt where barometer readings are 

 relatively high. Dr. LUCKY Kit thinks that anticyclones make the circuit of the globe, forming, dispersing, 

 ami reforming during their passage, and that it is in this manner that the temperate zone is bridged, .m<l 

 the union between tropical and polar air cin-ulation established. He supposes, moreover, that between 

 each of the anticyclones the northern segments of extensive cyclonic depressions, travelling eastward, 

 <-l>t rude, while the anticyclones move with them. 



Mr. l;i SHELL assumed the rate of translation of these hypothetical systems of high pressure over the 

 Southern Ocean to be about 460 miles per day ; were his theory correct, however, a vessel of average 

 peed running eastward between the 30th and 40th or even the 45th parallels of latitude would be over- 

 taken by a succession of anticyclones. On the approach of each the wind would commence to freshen 

 from some point between South and West with a rising barometer, subsequently veering to Northward 

 with a falling barometer and moderating ; and a vessel making the passage homeward from Australia riA 

 the Cape of Good Hope in about the 30th parallel would meet these high-pressure systems, moving in the 

 opposite direction, and experience a similar sequence of changes repeated in rapid succession. 



Now it is well known that the reverse obtains; winds experienced by vessels running eastward 

 commence to freshen from a northerly or north-westerly direction with a falling barometer; back to the 

 south westward or southward with a rising barometer and moderate. 



To the navigator making the passage between the meridian of Cape Point and that of Cape Leeuwin or 

 of Stewart Island the overtaking depressions are of so marked a character, and the influence they exert 

 upon the progress of his vessel so considerable, that there can be in his mind at least no doubt as to their 

 dominance over the weather. 



The evidence afforded by the synchronous daily charts under notice, as well as by chart* of average 

 barometrical pressure, is, moreover, in direct contradiction to Mr. RrssEU.'s theory, while, on the other 

 hand, it can be proved conclusively by reference to such charts that the anticyclones of the great oceans 

 are permanent systems of high pressure. 



It must be admitted, nevertheless, that the appearance over the extreme west of Australia, on the 

 daily weather charts that are drafted, of these anticyclones, month after month, and their regular progress 

 crow the island continent conveys the impression that they are visitors from the Indian Ocean and might 

 have formed, as Mr. KCSSELJ. supposed, thousands of miles to the westward. 



Southern Hrmitphrr* Surfac* Air CircuUtioo,' by WILLIAM J. 8. LOCKTM, M.A. (Ctoteb.), Ph.D. (OOUin|M). 

 F.K.AJ&, Chief AaiirsM, Solar Phrrfes Ofassmtory. 



