August 2 2, 1878] 



NATURE 



451 



pack. There can be no doubt that in the year 1S61 Dr. Hayes 

 gazed over an expanse of open water where, in 1875-76, Capt. 

 Nares studied the conditions of palKocrj'stic ice. It is evident, 

 therefore, that the Polar basin, or at all events such portions of 

 it as have been hitherto reached, is neither open sea nor con- 

 tinuous ice, but a fatal compromise between the two, an enor- 

 mously heavy pack formed by the piling up and crushing 

 together of the floe of successive years, in frequent movement, 

 breaking up and shifting according to the prevailing direction of 

 the wind, and leaving open, now here and now there, lanes and 

 vistas of deceptive open water which may be at any moment 

 closed and converted into a chaotic mass of hurtling floe-bergs 

 by a hurricane fx-om another direction. It seems, however, that 

 in certain seasons there is more open water in the direction of 

 Grinnell's Land and Smith's Sound than in others, and that 

 there are also years comparatively favourable for the northward 

 route following the lead of Franz- Josef Land ; and there seem 

 now to be only two plans, one nearly as hopeless as the other, to 

 choose between in any future attempt — either to' establish several 

 permanent Polar stations, as proposed by Lieut. Weyprecht, 

 and already initiated at one point, so far as preliminaries are 

 concerned, by Capt. Tyson and Capt. Howgate, and to seize the 

 opportunity of running north in early autumn from the station 

 where the sea appears most open, or to run as far north as possi- 

 ble at enormous expense, with a great force of men and abun- 

 dance of provisions and paraffin oil, and push northwards 

 during the arctic winter by a chain of communicating stations 

 with ice-built refuge huts. It seems possible that in a cold 

 season, with the pack in the condition in which Markham 

 found it in 1876, some progress- might be made in this way if it 

 were conceivable that the end to be gained was worth the expen- 

 diture oi so much labour and treasure. 



The Antarctic Kegions. — But little progress has been made 

 during the last quarter of a century in the actual investigation of 

 the conditions of that vast region which lies within the parallel 

 of 70° S. Some additional knowledge has been acquired, and 

 the light which recent inquiries have thrown upon the general 

 plan of ocean circulation and the physical properties of ice, have 

 given a new direction to what must partake for some time to 

 come of the nature of speculation. 



From information derived from all sources' up to the present 

 time, it may be gathered that the unpenetrated area of about 

 4,700,000 square miles surrounding the South Pole is by no 

 means certainly a continuous " Antarctic Continent," but that it 

 consists much more probably partly of comparatively low conti 

 neiital land, and partly of a congeries of continental (not oceanic) 

 islands, bridged between and combined, and covered to the 

 depth of about 1,400 feet, by a continuous ice-cap; with here 

 and there somewhat elevated continental chains, such as the 

 groups of land between 55'' and 95° W., including Peter the 

 Great Island and Alexander Land, discovered by Billingshausen 

 in 1 82 1, Graham Land and Adelaide Island, discovered by 

 Biscol in 1832, and Louis Philippe Land by D'Urville in 1838, 

 and at least one majestic modern volcanic range discovered by 

 Ross in 1 84 1 and 1842, stretching from Balleny Island to a 

 latitude of 78=' S., and rising to a height of 15,000 feet. It 

 .seems, so far as is at present known, that the whole of the 

 antarctic land, low and high, as well as the ice-cap of which a 

 portion of the continuous continent may consist, is bordered to 

 some distance by a fringe of ice, which is bounded to seaward by 

 a perpendicular ice-cliff, averaging 230 feet in height above the 

 sea-level. Outside the cliff tSLjloe, which attains near the barrier 

 a thickness of about 20 feet, and in some places by piling a con- 

 siderably greater thickness, extends northwards in winter to a 

 distance varying according to its position with reference to the 

 southward trending branches of the equatorial current ; and this 

 floe is replaced in summer by a heavy drifting pack with 

 scattered ice-bergs. Navigating the Antarctic Sea in the 

 southern summer, the only season when such navigation is 

 possible, it has been the opinion of almost all explorers, that 

 after forcing a passage through an outer belt of heavy pack 

 and ice-bei-gs, moving as a rule to the north-westward, and 

 thus fanning out from the ice-cliff in obedience to the prevailing 

 .south-easterly winds, a band of comparatively clear water is to 

 be found within. 



Several considerations appear to me to be in favour of the 

 view that the area round the South Pole is broken up and not 

 continuous land. For example, if we look at a general ice-chart 

 we find that the sea is comparatively free from icebergs, and 

 that the deepest notches occur in the "Antarctic Continent" at 



three points, each a little to the eastward of south of one of the 

 great land masses. Opposite each of these notches a branch of 

 the equatorial current is deflected southwards by the land, and is 

 almost merged in the great drift-current which sweeps round the 

 world in the Southern Sea before the westerly anti-trades. But 

 while the greater portion of the Brazilian current, the East 

 Australian current, and the southern part of the Agulhas current 

 are thus merged, they are not entirely lost ; for at these points of 

 junction wih the drift-current of the westerlie.-, the iso- 

 bathytherms are slightly deflected to the southwards, and it is 

 opposite these points of junction that we have comparatively open 

 sea and penetrable notches in the southern pack. But we have 

 not only the presumed effect of this transfer of warmer water to 

 the southwards ; we were able to detect its presence in the 

 Challenger by the thermometer. Referring to the result of a 

 serial temperature sounding on February 14, 1874, with a 

 surface temperature of 29° F. at a depth of from 300 to 400 

 fathoms, there is a band of water at a temperature of more than 

 half a degree above the freezing-point. That this comparatively 

 warm water is coming from the north there is ample proof. We 

 traced its continuity with a band at the same depth gradually 

 increasing in warmth to the northward, and it is evident that its 

 heat can be derived from no other source, and that it must be 

 continually receiving new supplies, for it is overlaid by a band 

 of colder water, tending to mix with it by convection. 



It is, of course, possible that these warm currents may by 

 coincidence be directed towards those notches already existing 

 in a continental mass of land ; but such a coincidence would be 

 remarkable, and there is certainly a suggestion of the alternative 

 that the "continent" may consist to so great anex'.ent of ice as 

 to be liable to have its outline affected by warm currents. 



In high southern latitudes it seems that all the icebergs are 

 originally tabular, the surface perfectly level and parallel with 

 the surface of the sea, a cliff about 230 feet high bounding the 

 berg. The top is covered with a layer of the whitest snow ; now 

 and then a small flock of petrels take up their quarters upon it, 

 and trample and soil some few square yards, but after their 

 departure one of the frequent snow showers restores it in a few 

 minutes to its virgin whiteness. The upper part of the cliff is 

 pale blue, which gradually deepens towards the base. When 

 looked at closely the face of the cliff is seen to be traversed by a 

 delicate ruling of faint blue lines, the lines being more distant 

 from one another above and becoming gradually closer. The 

 distance between the well-marked lines near the top of a berg 

 may be of a foot or even more, while near the surface of the 

 water it is not more than two or three inches, and the space 

 between the blue lines have lost their dead whiteness and have 

 become hyaliue or bluish. The blue lines are very unequal in 

 the.r strength and in their depth of colouring ; sometimes a 

 group of very dark lines gives a marked character to a part of a 

 berg. Between the stronger blue lines near the top of the cliff 

 a system of closer lines may be observed, marking the division 

 of the ice by still finer planes of lamination ; but in the nar- 

 rower spaces near the water-line they are blended and lost. 

 The blue lines are the sections of sheets of clear ice ; the white 

 intervening bands are the sections of layers of ice where the 

 particles are not in such close contact — ice probably containing 

 some air. 



The stratification in all these icebergs is, I believe, originally 

 horizontal and conformable, or very nearly so. In many, while 

 melting and beating about in the sea, the strata become inclined at 

 various angler, or vertical or even reversed ; in many they are 

 traversed by faults, or twisted, or contorted, or displaced ; but I 

 believe that all deviations from a horizontal arrangement are due 

 to changes taking place in the icebergs themselves. 



I think there can be no doubt, from their shape and form, and 

 their remarkable uniformity of character, that these great table- 

 topped icebergs are prismatic blocks riven from the edge of the 

 great antarctic ice-sheet. I conclude, therefore, that the upper 

 part of the iceberg, including by far the greater part of its bulk, 

 and culminating in the portion exposed above the surface of the 

 sea, was formed by the piling up of successive layers of snow 

 during the period, amounting perhaps to centuries, during which 

 the ice-cap was slowly forcing its way over the low land, and 

 out to sea over a long extent of gentle slope, until it reached a 

 depth considerably beyond 200 fathoms, when the lower specific 

 w eight of the ice caused an upward strain which at length over- 

 came the cohesion of the mass, and portions were rent off and 

 floated away. The icebergs when they are first dispersed float 

 in from 200 to 250 fathoms ; when, therefore, they have been 



