15 



eastward ,,f successive ] preuu u over the. South,-,-,, . . llivo | y ., .i, j, coMumiy 



being drawn from lower latitude, in front of central a,-,,,, of de,,,,-^,,,,,, w |, | ^ in 



the frigid zone and being still further chilled l.y the mixing of air of |H ,| iir origin, Iwre th, At,i.,r,-ti e M 

 cold wind. 



This exposition of surface wind circulation in high latitude,,, whirl, based on a clow examination of 

 the results of observations represented on the daily charts, was offered l,y tl, ^ 



Climatology of South Victoria Land in Part I. of this work. The proportion I,*., rinot IK-,,, . !. t intl 

 and extended to equatorial regions by Dr. W. J. LOCKYEK,* who suggests that the warn air cummU 

 circulating in front of the baric minima of eastward moving depressions are of equatorial origin, a,,.| tint 

 after they have traversed the southern and western segments of their circuit they r-j.,in th,- w'-*t. 

 current, and so return by the trade wind circulation to the equator on the eastern si.).- ,,f u.tirydones. 



This, as the writer understands it, is in effect the suggestion put forward, and it i< a 1 ,r..|Hiii.,n with 

 which, in the main, he is in accord. 



ANTICYCLONES OF THE SUB-TROPICAI, BELT. 



In regard to this subject Dr. LOCKYEU, in the work already quoted, favours the views held l,y the late 

 Mr. H. C. RUSSELL, F.R.S., C.M.G., in regard to these ocean anticyclones and tin <ure U-lt. I!.- 



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

 anticyclones moves eastward, following one another in quick succession, and 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. LOCKYEU thinks that anticyclones make the circuit of the globe, forming, dispersing, 

 and reforming during their passage, and that it is in this manner that the temperate zone is bridged, and 

 the union between tropical and polar air circulation established. He supposes, moreover, that between 

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

 obtrude, while the anticyclones move with them. 



Mr. RUSSELL 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 

 speed running eastward between the 30th and 40th or even the 45th parallels of latitude would he 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 rid 

 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 charts of average 

 barometrical pressure, is, moreover, in direct contradiction to Mr. Kr>sKU.'s theory, while, on the 

 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 wwl f An-tralia, on the 

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

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

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



* ' Southern Hemisphere Surface Air Circulation,' by WILLIAM J. S. LOCKTBK, M.A. (C'.ntab.), Ph.D. (O6Uingo), 

 F.R.A.S., Chief Assistant, Solar Physics Observatory. 



