On the shores of Greenland the ebb tide flows towards the coast, apparently as though it passes under the land, and the flood tide recedes from the shore; and in those regions the sea is almost universally found deeper as you approach the shore.[36] When the whales become scarce, experience has taught the whalers to seek for them near the shore, as if at certain seasons they retired to it, and then disappeared. Captain Symmes imagines that the sea extends quite through the spheres, about Greenland, and that the whales suddenly migrate either to the _mid-plane-space_, or to the seas on the opposite side; which he alleges to be the case with several other species of fish, as well as seals; all of which, he supposes, breed in the _mid-plane-space_. The reasons that induce him to adopt this conclusion are various; such as, that fish have been thrown up by the eruption of a volcano in South America[37]――herring appearing in such immense numbers at certain seasons of the year――the whales seeming to pass under Greenland――two seals having been once caught in Lake Ontario, which is said to be unfathomable, although this lake is many degrees south of where the seals have ever before been known to come――and the various species of fish in our northern lakes which appear and disappear at certain periods. That the exterior seas in some places communicate with the interior seas, is rendered probable by various other circumces; such as currents running continually into the Mediterranean, and no visible outlet to the water thus continually flowing in. It is scarcely probable that evaporation could carry off all the water supplied by the straits of Gibraltar――the white sea being more salt at the head than at the foot――the tides being higher in the Baltic than the Mediterranean――white foxes having been forced up by the waters of the sea (as Symmes undertakes to prove) in the northern regions――the peculiarities of the tremendous whirlpool on the coast of Norway, called the Maalstroom, which sucks in, and discharges the waters of the sea with great violence――and those observable in the Bay of Biscay, which are said to be unfathomable. FOOTNOTES: [31] EARTHQUAKES.――M. Biot, after detailing the phenomena of the earthquake, on the 22d of February, 1822, concludes an interesting paper with these observations:――