always in the same place, as the Gulf Stream (§ 126) is not always in one place. It probably is always where the waters of the under currents are brought to the surface; and this, we may imagine, would depend upon the freedom of ingress and egress for the currents. Their course may perhaps be modified more or less by the ice on the surface, by changes, from whatever cause, in the course or velocity of the surface current, for obviously the under current could not bring more water into the frozen ocean than the surface current would carry out again, either as ice or water. Exploring parties may have been near this open sea without perceiving the warmth of its climate, for every winter, an example of how very close warm water in the sea and a very severe climate on the land or the ice may be to each other is afforded to us in the case of the Gulf Stream and the Labradorlike climate of New England, Nova Scotia, and Newfoundland. In these countries, in winter, the thermometer frequently sinks far below zero, notwithstanding that the tepid waters of the Gulf Stream may be found with their summer temperature within one day's sail of these very, very cold places.
429. Dr. Kane.—Dr. Kane reports an open sea north of the parallel of 82°. To reach it, his party crossed a barrier of ice 80 or 100 miles broad. Before gaining this open water, he found the thermometer to show the extreme temperature of—60°. Passing this ice-bound region by travelling north, he stood on the shores of an iceless sea, extending in an unbroken sheet of water as far as the eye could reach towards the pole. Its waves were dashing on the beach with the swell of a boundless ocean. The tides ebbed and flowed in it, and I apprehend that the tidal wave from the Atlantic can no more pass under this icy barrier to be propagated in the seas beyond, than the vibrations of a musical string can pass with its notes a fret upon which the musician has placed his finger. The swell of the sea cannot pass wide fields or extensive barriers of ice; for De Haven, during his long imprisonment and drift (§ 475), found the ice so firm that he observed regularly from an artificial horizon placed upon it, and found the mercury always "perfectly steady." These tides, therefore must have been born in that cold sea, having their cradle about the North Pole. If these statements and deductions be correct, then we infer that most, if not all the unexplored regions about the pole are covered with deep water; for, were this unexplored area mostly land or shallow water, it could
