March 3, 1898] 



NA TURE 



425 



We know that the southern continent is a region of actual 

 volcanic activity ; but the extent, nature, and effect of that 

 activity remain to be ascertained. 



On the Antarctic Circle land has been reported at numerous 

 points, south of Australia and the Indian ocean, but it is un- 

 known whether what has been seen indicates islets and rocks, or 

 a continuous coast-line. 



Dr. Murray has pointed out that the whole southern continent 

 is certainly not bounded by such an ice-wall as was seen by Sir 

 James Ross, and is not covered by an ice-cap. But the extent 

 alike of the ice-cap and of the uncovered land is unknown. 



We are ignorant of the distribution of land and sea, and of 

 ice and watei in summer, and of the causes which influence such 

 distribution. 



These are some of the geographical problems to be solved. 

 The investigation of each one of them will lead to further dis- 

 coveries as yet undreamt of, which must needs be of the deepest 

 interest to geographers. 



There are eminent men present who will no doubt refer to the 

 results of Antarctic exploration as regards other branches of 

 science. Combined together they make the discovery of the 

 unknown parts of the Antarctic region the greatest and most 

 important work that remains for this generation of explorers to 

 achieve. 



Meteorology and A.ntarctic Exploration. 



Dr. Alexander Buchan stated that the remarks he was about to 

 make would have exclusive reference to the first two paragraphs of 

 Dr. Murray's address, under the heading of " The Atmosphere " ; 

 or, rather, more immediately to the relation between mean atmo- 

 spheric pressure and prevailing winds. He supposed he had 

 been asked to speak on this occasion, from the extensive and 

 minute knowledge of the subject he had necessarily acquired in 

 the preparation of the reports on atmospheric and oceanic circu- 

 lation which were published as two of the reports of the scientific 

 re.<ults of the voyage of H. M S. Challenger. 



The former of these reports, on atmospheric circulation, is 

 accompanied by twenty-six maps, showing by isobars for each 

 month and the year the mean pressure of the atmosphere, and 

 by arrows the prevailing winds of the globe, on hypsobathy- 

 metric maps, or maps showing by shadings the height of the land 

 and the depth of the sea; first on Gall's projection, and second 

 on north circumpolar maps on equal surface projection. The 

 isobars are drawn from mean pressures calculated for 1366 places, 

 and the winds from even a larger number of places, distributed 

 as well as possible over the whole globe. It is also of importance 

 to note that averages of pressure and prevailing winds are pub- 

 lished with the report — an accompaniment to the maps of mean 

 atmospheric pressure and prevailing winds of the globe not yet 

 given in any other series of maps of mean pressure and prevail- 

 ing winds. 



This then is the work undertaken and published in these 

 reports, which occupied seven years in preparing, as time could 

 be spared from official duties. The result of the charting of the 

 pressure and prevailing winds is this : stand with your back to 

 the wind, then the centre of lowest pressure that causes the wind 

 will be to the left in the northern hemisphere, and to the right 

 hand in the southern hemisphere, a relation well known as Buys 

 Ballot's law. In. charting the 1366 pressures and the relative 

 prevailing winds, no exception was found in any of the two hemi- 

 spheres. This is one of the broadest generalisations science can 

 point to. 



Some years ago a theory of atmospheric circulation was pub- 

 lished by the late Prof. Ferrel which, as it is not accordant 

 with the broad resulcs arrived at in the report of atmospheric 

 circulation in the Challenger Reports, calls for serious considera- 

 tion on account of its bearing on any attempt proposed to be 

 undertaken for the exploration of the Antarctic regions. 



One of the more recent expositors of this theory is Prof. Davis, 

 of Harvard College, who, in his " Elementary Meteorology," 

 gives an admirable exposition of the results now arrived at by 

 the various workers in meteorology, and of the opinions and 

 theories promulgated by different meteorologists in difif'erent de- 

 partments of the science. The book is largely used in secondary 

 schools and colleges of the United States, and these views are 

 all but universally held there, and are now spreading over 

 other countries. 



The following extracts from Davis's book fairly represent 

 these views as generally entertained. 



" The surface winds of the temperate latitudes, and the high- 



NO. 1479. VOL. 57] 



level currents above them, sliding swiftly along on their steep 

 poleward gradients, must all be considered together. They 

 combine to form a vast aerial vortex or eddy around the pole. 

 In the northern hemisphere this great eddy is much interrupted 

 by continental high pressure in winter, or low pressure in 

 summer, and by obstruction from mountain ranges, as well as 

 by irregular disturbances of the general circulation in the form 

 of storms" (p. no). 



Now the facts of observation do not support the theory of 

 the existence, at any season of the year, of a low barometric 

 pressure, or an eddy of winds, round or in the neighbouring regions 

 of the north pole. Observations do not show us any prevail- 

 ing winds blowing homewards to the north pole at any time 

 of the year. Further, no low barometric pressure occupies the 

 immediate polar region in any month ; but instead, the opposite 

 holds good for the four months from April to July. In April 

 and May the mean atmospheric pressure is higher in the region 

 of the pole than it is anywhere in the northern hemisphere 

 north of 43° lat. N. ; and in June and July, also higher than it 

 is anywhere north of 55° lat. N. Now the higher pressure in 

 these four months necessitates the existence of upper currents in 

 order to maintain this high pressure about the north pole. 

 These upper currents toward the pole are exactly opposed to 

 the requirements of the theory, which intimates that the upper 

 currents in the region of the pole must necessarily blow not 

 towards but from the pole. 



The actual centre in this hemisphere, north of the tropics, 

 towards which the winds on or near the surface of the earth 

 blow, is not the north pole ; but, in the winter months, the 

 low barometric depressions in the north of the Atlantic and 

 Pacific respectively, and in the summer months, the low baro- 

 metric depressions in the Eurasian and North American con- 

 tinents ; and the sources out of which the prevailing winds blow, 

 in the winter months, the high pressure regions in Siberia and 

 North America ; and in the summer months, the high pressure 

 regions lying northward of these continents, which, as already 

 explained, are virtually the polar region itself. These are the 

 facts in all regions where the winds, according to the theory, 

 become winds blowing over the earth's surface. 



As regards the southern hemisphere, Prof. Davis states 

 that— 



" In the southern hemisphere the circumpolar eddy is much 

 more symmetrically developed." Again, " the high pressure 

 that should result from the low polar temperatures is therefore 

 reversed into low pressure by the excessive equatorward centri- 

 fugal force of the great circumpolar whirl ; and the air thus held 

 away from the polar regions is seen in the tropical belts of high 

 pressure" (pp. no, 111). 



The interpretation of this is that the remarkable low pressure 

 region of the southern hemisphere is continued southward 10 the 

 south pole itself, the pressure diminishing all the way ; and that 

 in the region of the south pole, the air currents poured thither- 

 wards along the surface of the earth, ascend, and thence pro- 

 ceed northwards as upper currents of such enormous intensity 

 and volume, that they pile up in the tropical region of the 

 southern hemisphere a mean sea-level atmospheric pressure 

 about an inch and a half more than the sea-level pressure near 

 the south pole whence it starts. Now, to bring the matter to 

 the business which this meeting of the Royal Society has taken 

 in hand — if this theory be true and supported by the facts of 

 observation, it is plain that no meteorologist could signify his 

 approval of any scheme that could be proposed for exploring the 

 Antarctic regions, it being obvious that these strong west-north- 

 westerly winds, if they blow vortically round and in upon the 

 pole, heavily laden, as they necessarily would be with the aqueous 

 vapour they have licked up from the Southern Ocean, would 

 overspread Antartica with a climate of all but continuous rain, 

 sleet, and snow, which no explorer, however intrepid and 

 enthusiastic, could possibly face. 



But is this the state of things ? Let it be at once conceded 

 that, as far south as about 55° lat. S. , the prevailing winds and 

 the steadily diminishing mean pressures on advancing south- 

 ward fairly well support the theory. South of this, however, 

 southerly and south-easterly winds begin to increase in fre- 

 quency, until from 60^ lat. S. into higher latitudes, they become 

 the prevailing winds. This is abundantly shown from the 

 winds charted on the maps of the Challenger Report, as well 

 as from the unanimous experience of all those who have 

 navigated this region from Ross to the present time. Thus the 

 p)oleward blowing winds from west-north-west in these summer 



