390 Transactions. — Miscellaneous . 



paratively slow, because water at 60° is denser than at 100°, 

 and at 100° than at 212°. Water heats slowly by conduction, 

 and the tendency is to move as a surface-water in the direc- 

 tion of the boundary where the temperature is least. In the 

 second bottle the hottest water at the bottom is less dense 

 than that at the top, and they are in a condition of unstable 

 equilibrium. The movements here must be up and down 

 rather than up and horizontal. These two examples illustrate 

 the movements of the waters of the ocean as I conceive them 

 in times past and present. 



Surface-movements are greater now than they were in 

 former times, whilst the reverse is the case in the matter of 

 depth-movements. But the surface-waters as they proceed 

 from the torrid zone outwards are constantly parting with 

 their heat, and as the waters as currents approach the colder 

 zones they also approach the depth-temperatures of the 

 waters in those zones. Were the waters of the earth of the 

 same temperature and density there would be no current- 

 movements either vertical or horizontal, and were the earth's 

 surface a plane vertical to the ecliptic there would be no 

 horizontal movements of the atmosphere — that is, there 

 would be no winds, as no other movement would be possible 

 but one at right angles to the surface, or what, in other words, 

 might be termed an up-and-down movement. And this brings 

 me back to the water and air oceans within the torrid zone. 

 That portion of the Arctic Ocean which is embraced within 

 the circumpolar zone extending from 5° to 10° may be sup- 

 posed to be almost free from currents, owing to the fact of 

 greater denir^ity combined with the circumstance of the near 

 approximation in temperature of the surface and deep waters. 

 Whatever movements there- may be must have a tendency 

 downwards, and thence in the direction of the warmer areas ; 

 for it must be remembered that the waters of the frigid zone 

 are not now fully maintained by the quantity of solar heat 

 given to that zone, but rather by the surplusage that finds 

 its way to the frigid zone from the other zones by means of 

 aqueous and atmospheric agencies. Thus, for example, 

 the movement of waters from the Pacific and Atlantic Oceans 

 towards the colder zones is an important means of conveying 

 heat, but the same thing may be said with respect to the 

 large rivers that pour their waters into the Arctic Oceaa 

 from Europe, Asia, and America. These warm areas of in- 

 flow occupy cardinal points with respect to each other on a 

 map of that ocean. Thus, Behring Sea is opposite to the 

 opening into the Atlantic Ocean, and the great Mackenzie 

 Eiver may be set down as being opposite the Obi and other 

 large rivers of Asia. 



Warm areas were specially noticed by Nordenskjold, and 



