NARRATIVE OF THE CRUISE. 417 



Eoss, D'Urville, and Wilkes saw both kinds of ice in the vicinity of the land, and 

 both Ross and D'Urville agree in stating that the icy cliffs, which are now known as 

 the " lee Barrier," are not to be seen when the land is high and mountainous ; for 

 instance, Eoss saw no barrier until he reached the extremity of the ridge of mountains 

 running irregularly north and south through Victoria Land, and D'Urville saw no icy 

 barrier opposite Adelie Land, but traced it for 60 mdes on the coast of what he supposed 

 to be Clarie Land, where Wilkes also saw it. Wilkes himself does not say where he saw 

 the ice cliffs and where the land ice, but calls them both the icy barriers. That they both 

 form a barrier to the land is undeniable, and so Wilkes was entitled to call both descrip- 

 tions of ice the "Barrier"; still it would have been an advantage to succeeding investi- 

 gators had Wilkes distinguished between the land ice which may by heavy gales or some 

 cause be broken up occasionally, and the ice cliff which one might as well attempt to pass 

 or to sail through as the Cliffs of Dover, and which is now the only description of ice called 

 the " Barrier." It does not appear that any other explorer except Eoss, D'Urville, and 

 Wilkes has seen the icy barrier, although most southern explorers have seen the ice 

 extending from the foot of the land. 



From the fact that two explorers only have succeeded in effecting a landing on 

 Antarctic shores proper, and that the land there is almost entirely covered with perpetual 

 snow and ice, it is evident that our knowledge of the geography and geology of the Antarctic 

 regions must necessarily be very limited. That a very considerable tract of land exists 

 south of the 65th parallel and between the meridians of 100° E. and 180° E., and also 

 between the meridians of 45° and 60° E., cannot be doubted, but whether this land is 

 continuous or broken up into a series of islands with shallow water between cannot at 

 present be stated with any great degree of certainty, for the ice in the vicinity of the 

 land so blocks up all approach to the coast and hides the shore that it is next to impos- 

 sible to say, with accuracy, where the land begins. It can, therefore, only be conjectured 

 from the state of the ice and the observed temperatures what the condition of the land is. 



Antarctic Temperatures. — The mean temperature of both the air and sea surface 

 south of the parallel of 62-£° S. is, even in summer, at or below the freezing point of 

 fresh water. 1 Between 60° and 62^° S. a sensible rise takes place, and a reading 

 as Inch as 38° has been recorded of both air and sea in March between these 

 parallels. Temperatures below the surface south of the 60th parallel had been taken 

 by Cook, Eoss, and Wilkes before the Challenger Expedition, but as the thermometers 

 used were not protected from pressure, the results obtained are not of much value, as 

 they are combinations of temperature and pressure due to depth. There is, however, 

 one marked peculiarity about the results obtained with these unprotected thermometers, 



1 Contributions to our knowledge of the Meteorology of the Antarctic Regions. Published by authority of the 

 Meteorological Committee, 1873. 



(naer. chall. exp. — vol. i.^-1884 ) 53 



