380 PHYSICAL GEOGrEAPHY OF THE SEA, AlTD ITS METEOROLOGY. 



helm ? What compass, and of Avhose workmanship, is that which 

 guides these delicate and graceful little argonauts from sea to 

 sea? Arriving off the "Stormy Capes," the flotilla is separated, 

 one division holding its way for the Pacific, the other hauling up 

 for the Atlantic, each bound on its high and secret mission. 

 They build, equip, and repair as they go ; the fleet is imperish- 

 able, but individual life in it is ephemeral. They die, these tiny 

 *' men o' war," one after another, but the same watchful Providence 

 that cared for them while living, now provides for their burial 

 being dead. The inanimate shell, drawn to distant seas by under 

 currents^ descends like autumnal leaves from depth to depth by 

 an insensible fall. In future times the seaman's sounding-rod 

 may reach the bottom on which it has fallen, and thus reveal to 

 man the secret paths of the sea, — or when the geological clock 

 next strikes the hour, the same little shell may, by some throe of 

 nature, be brought up to the surface, and spread out in its 

 marl bed, to fertilize and make fruitful unknown lands. 



7-il. There is a movement of the waters of the ocean which, 

 Drift described, though it bc a translation, yet it does not amount 

 to what is known to the mariner as " current," for our nautical 

 instruments and the art of navigation have not been brought to 

 that state of perfection which will enable navigators generally to 

 detect as currents the flow to which I allude as drift. If an object 

 be set afloat in the ocean, as at the equator, it would, in the course 

 of time, even though it should not be caught up by any of the 

 known currents, find its way to the icy barriers about the poles, 

 and again back among the tepid waters of the tropics. Such an 

 object would illustrate the drift of the sea, and by its course would 

 indicate the route which the surface-waters of the sea follow in 

 their general channels of circulation to and fro between the 

 equator and the poles. 



742. The object of Plate IX., therefore, is to illustrate, as far as 

 Plate IX. the present state of my researches enable me to do, 

 the circulation of the ocean as influenced by heat and cold, and to 

 indicate on one hand, the routes by which the overheated waters 

 of the torrid zone escape to cooler regions, and to point out, on 

 the other, the great channel- ways through which the same waters, 

 after having been deprived of this heat in the extra-tropical or 

 polar regions, return again towards the equator ; it being assumed 

 that the drift or flow is from the poles when the temperature of 

 the surface water is helow, and from the equatorial regions when 



