A Text-Book of Oceanography. By J. T. Jenkins (Constable. 15s.
net.)—Deep-sea research has made great progress in recent times, and Dr. Jenkins's lucid survey of the subject corrects many prevalent misconceptions. As he says, this is the first modern text-book of oceanography in English. He discusses in turn the extent of the oceans and the nature of the ocean floor, which is for the most part a plain ; oceanic deposits ; the temperature of the sea and the properties of sea-water ; waves and tides ; and ocean currents. The chapters are illustrated with a number of diagrams. Dr. Jenkins gives a good account of the Florida Current, inaccurately called the Gulf Stream, gime it does not come from the Gulf of Mexico. He illus- trates the value of oceanography by pointing not that " the growth of the Norwegian pine for the following year and the autumn crops of barley and legumes depend on the sea temper. ature " as observed in the Florida Current off the coast of Norway. " A high temperature of the Atlantic drift-water in May is followed by a good yield of the autumn crops on shore, as well as by an early spawning of the cod on the Lofoten Banks-in the following spring and a diminution of the pack-ice in Barents Sea two years later." Changes in the sea temperature affect the movements of shoals of fish, so that the patient man of science who cruises about, recording the temperature of the sea with his submersible thermometer, is a useful guide for the trawler.
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