. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. 778 DEPTHS OF THE OCEAN the 30th meridian west (Fig. 567). We see that the water- layer limited by the isotherm of io° C. is relatively thin in proportion to the depth of the ocean. The genuine warm- water layers with temperatures exceeding 150 C. reach only to 30° south and north, and are only 200 to 300 metres thick. The whole layer above io° C. has a thickness varying between 300 and 700 metre
. The depths of the ocean; a general account of the modern science of oceanography based largely on the scientific researches of the Norwegian steamer Michael Sars in the North Atlantic. Oceanography. 778 DEPTHS OF THE OCEAN the 30th meridian west (Fig. 567). We see that the water- layer limited by the isotherm of io° C. is relatively thin in proportion to the depth of the ocean. The genuine warm- water layers with temperatures exceeding 150 C. reach only to 30° south and north, and are only 200 to 300 metres thick. The whole layer above io° C. has a thickness varying between 300 and 700 metres (or between -^ and ^ of the depth of the ocean). Now it was only a part of this small layer which was examined by Hensen's expeditions, and consequently the results must necessarily be incomplete. Equator. Lat. N. leten 0 30° 20u 10' 10 20 30 40 50 60. 2500 Fig. 567.—Distribution of Temperature in the Atlantic along the thirtieth Meridian of West Longitude. (From Schott.) Distribution of whales. In order to understand the abundance of animal life in various parts and at various depths of the Atlantic, it is very useful to review our knowledge of the distribution of whales in that ocean. I agree with Eschricht in dividing the whales into different biological groups according to the food on which they live. One group feeds on " plankton," another on both plankton and fishes, and a third group on squids. Genuine " plankton whales " are the arctic " right " whale (the Greenland whale, Balcena mysticetus, see Fig. 568), and the boreal blue whale (Balcznoptera musciilus, Fig. 569). By the aid of their enormous tongues they press the water out of their mouths between the whalebone lamellae, thus filtering the water and retaining the minute organisms (see Fig. 570).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1912
