322 Voyages of Discovery and Survey. 



sea-water decreased in volume until it reached 22°, when it expanded 

 a little, and continued to do so down to a temperature of between 

 19° and 18°, when it expanded suddenly, and became ice with a 

 temperature of 28°. According to M. Erman, salt-water of the 

 specific gravity of 1'027 diminishes in volume down to 25° Fahr., 

 not reaching its maximum density until congelation. The tempera- 

 ture of the most dense sea-water observed so constantly by Sir James 

 Ross, is about that which numerous experiments shew as that of the 

 greatest density of fresh water. Dr Hope and Pi'ofessor Moll found 

 the latter to be between 39°'5 and 40° Fahr., and Professor Hall- 

 strom states it to be 39°"394 Fahr. The observations of Sir James 

 Ross would shew that the temperature of the ocean-waters, which 

 may be considered to vary in specific gravity from about 1'027 to 

 1-028, is the same with fresh water, and the mass of evidence he 

 adduces, supposing no instrumental errors, would prove that the 

 temperature of 39°'5 is that of the most dense water of the sea, and 

 if not corresponding with experiments in the cabinet, shews either 

 that there is some modifying cause beneath the waters of the ocean, 

 producing a higher temperature than should otherwise be, or that 

 there were sources of error in the cabinet experiments not observed. 



It did not escape the Commander of this voyage, that the uniform 

 temperature of so much of the ocean might be favourable for the 

 passage of marine animals from northern to southern regions, if the 

 animals were such as to disregard the pressure of water under the 

 equator and in the tropics. He observes that arctic marine creatures 

 might pass to antarctic regions with only a difference in temperature 

 of 5°, and a pressure of 2000 feet of water in the tropics. 



In the region of Victoria Land we see a striking example of the 

 extension of marine life, and of aquatic mammalia and birds dependent 

 upon it, beyond terrestrial vegeiable life and the animals consuming 

 it. To this, no doubt, the equal temperature of the mass of waters 

 beneath certain depths gives great aid ; and, as a whole, these tempe- 

 ratures]! are less variable in the sea, and fall less low than in the 

 atmosphere, the covering of ice protecting the waters from the in- 

 tensity of cold to which they would be otherwise subject. 



Live Corals were taken up from the depth of 1620 and 1800 feet, 

 off Victoria Land, and from the same situations Chitons and other 

 molluscs, with >SVrj3MZ« adhering to stones and shells, were obtained.* 

 Looking at the temperature of the sea obtained off Victoria Land by 

 Sir James Ross, and the probable changes efl'ected during the winter 



* These corals were examined by ilr Charles Stokes, who found them to con- 

 sist of three species of Lepralia, lietepora cellulosa, Hornera frondiculata (Lamou- 

 rouxj, Primnoa liossii, Melitoca Australis, and Madrepora fissurata. He remarks 

 that Primnoa lepadifera is found in from 150 to 300 fathoms, off the coast of 

 Norway, and Professor Forbes is given as authority for a species of Primnoa in 

 278 fathoms olT Stateu Land. 



