Note 136 — Chapter IV

"This inland sea, though the smallest of the great chain with which it is connected, is of such extent, that vessels in crossing it lose sight of land, and must steer their way by the compass; and the swell is often equal to that of the ocean. During the winter, the northeast part of Ontario, from the Bay of Quinté to Sacket's Harbor, is frozen across; but the wider part of the lake is frozen only to a short distance from the shore. Lake Erie is frozen still less; the northern parts of Huron and Michigan more; and Superior is said to be frozen to a distance of seventy miles from its coasts. The navigation of Ontario closes in October; ice-boats are sometimes used when the ice is glare (smooth). One, mentioned by Lieutenant de Roos, was twenty-three feet in length, resting on three skates of iron, one attached to each end of a strong cross-bar, fixed under the fore-feet, the remaining one to the stern, from the bottom of the rudder; the mast and sail those of a common boat: when brought into play on the ice, she could sail (if it may be so termed) with fearful rapidity, nearly twenty-three miles an hour. One has been known to cross from Toronto to Fort George or Niagara, a distance of forty miles, in little more than three quarters of an hour; but, in addition to her speed before the wind, she is also capable of beating well up to windward, requiring, however, an experienced hand to manage her, in consequence of her extreme sensibility of the rudder during her quick motion."—Martin's History of Canada.

"The great earthquake that destroyed Lisbon happened on the 1st of November, 1755, and on Lake Ontario strong agitations of the water were observed from the month of October, 1755."—Lettera Rarissima data nelle Indie nella Isola di Jamaica a 7 Julio del 1503 (Bassano, 1810, p. 29).

"From some submarine center in the Atlantic, this earthquake spread one enormous convulsion over an area of 700,000 square miles, agitating, by a single impulse, the lakes of Scotland and Sweden, and the islands of the West Indian Sea. Not, however, by a simultaneous shock, for the element of time comes in with the distance of undulation; and, together with this, another complexity of action in the transmission of earthquake movements through the sea, arising from the different rate of progression at different depths. In the fact that the wave of the Lisbon earthquake reached Plymouth at the rate of 2.1 miles per minute, and Barbadoes at 7.3 miles per minute, there is illustration of the law that the velocity of a wave is proportional to the square root of its depth, and becomes a substitute for the sounding line in fixing the mean proportional depth of different parts of this great ocean."—Humboldt.