12 THE ROSS SEA 



year. It is doubtful whether even in the coldest month (July), McMurdo Sound was 

 completely frozen over, even when the mean temperature was -17° F. (-27° C). 

 Usually there was a long dai'k streak of open water about 15 to 20 miles off the 

 land, as sliown in the drawing by Mr. K. Craigie from an inferior photograph, 

 showing the Western Mountains. To the north of Black Sand Beach, about one 

 mile north of Cape Royds, there was open sea most of the winter. 



Murray {op. cit. p. 373) quotes good evidence to show that at times there was a 

 southerly current coming down from the direction of Cape Royds as far as Black 

 Sand Beach, about a mile north of Cape Royds. Thence the current turned west- 

 Avards across McMurdo Sound, and thence northwards towards Granite Harbour and 

 the Nordenskjold Ice Barrier Tongue. 



The large number of stranded bergs along the west coast of Ross Sea renders it 

 probable that the current, ou the whole, has a northerly set from McMurdo Sound 

 along its western shores. 



Strong off-shore winds from the Western Mountains, often immediately preceded 

 by southerly and south-easterly blizzards, would tend to give the water of Ross Sea a 

 clockwise rotation, which would be further accelerated by the easterly winds of King 

 Edward VII. Land. It seems very possible that the water of Ross Sea moves as a 

 gigantic eddy, the southern edge of which passes under the Ross Barrier proper, while 

 its south-western portion passes under the Barrier to the south of Ross Island and 

 flows northerly up McMurdo Sound.* 



Temi^erature. We have no sufficient data on the subject of the horizontal 

 distribution of temperature over Ross Sea, so the following suggestions are very 

 tentative. 



In reference to the vertical distributionof temperature we may quote the following 

 important observation by Sir J. C. Ross, quoted by Commander Hepworth : f 



" On January 6, 1841, at noon, they (the Erebus and Terror) were in latitude 

 68° 17' S., longitude 175° 21' E., and found that they had been set twenty-six miles 

 to the S.E, by the current during the previous two days. Here the temperature of 

 the water at 600 fathoms was found to be 39-8° F. ; at 450 fathoms, 39-2° ; at 300 

 fathoms, 38*2° ; at 150 fathoms, 37-5° ; and at the suril\ce 28° F." 



Ross's thermometers were not protected against pressure by being sealed up in a 

 strong outer glass tube as are modern thermometers. Nevertheless, this inversion of 

 temperature with depth cannot all be ascribed to increase of pressure on the bulb 

 of the thermometer. It may be mentioned that at a depth of over 620 fathoms, at 

 the Drygalski Glacier, J. K. Davis on the Nimrod registered a temperature of about 

 40° F. This was so high that we discredited it at the time (February 5-6, 1909), 



* Dr, W. S. Bruce and R. C. Mossman of the Scottish National Antarctic Expedition, 1902-4, hold 

 that a similar eddy exists in Weddell Sea. Lieutenant Filchner in the Deutsckland experienced a similar 

 current circulation, as proved by the direction of drift of his ship. 



t "National Antarctic Expedition," 1901-4. "Meteorology," part i. p. 420, 



