"The average wave was, I believe, fully equal to that of my sight on the paddle-box, or more than 15 feet, and the _mean highest waves_, not including the broken or acuminated crests, rose about 43 feet above the level of the hollow occupied at the moment by the ship. It was a grand storm-scene, and nothing could exceed the pictorial effect of the partial sunbeams breaking through the heavy masses of clouds." From the time taken by a regular wave to pass from stern to stem, Dr. Scoresby calculated its velocity at 2875 feet in each minute, or 32·67 English statute miles in an hour. The mean length of the wave-ridges, was from a quarter to a third of a mile. To those who might be inclined to doubt the accuracy of these measurements, the remark may suffice that our celebrated countryman had been for years engaged in the northern whale-fishery, where he had ample opportunities for practising his eye in measuring distances. Besides, the conclusions of many other trustworthy observers coincide with the evaluations of Dr. Scoresby. Thus Captain Wilkes, commander of the U. S. Exploring Expedition, found the height of the waves near Orange Harbour, where they rose higher and more regular than at any other time during the cruise, to be thirty-two feet (depression and altitude), and their apparent progressive motion about twenty-six and a half miles in an hour. Sir James Ross calculated the height of the waves on a strongly agitated sea at twenty-two feet, and, according to the French naturalists who sailed in the frigate "La Venus," on her voyage round the world, the highest waves they met with never exceeded that measure. Thus, according to the joint testimony of the most eminent nautical authorities, the waves in the open sea never attain the mountain-height ascribed to them by the exuberant fancy of poets or exaggerating travellers. But when the tempest surge beats against steep crags or rocky coasts it rises to a much more considerable height. The lighthouse of Bell Rock, though 112 feet high, is literally buried in foam and spray to the very top during ground-swells, even when there is no wind. On the 20th November, 1827, the spray rose to the height of 117 feet above the foundation or low-water mark, which, deducting eleven feet for the tide that day, leaves 106 feet for the height of the wave. The strength of that remarkable edifice may be estimated from the fact, that the power of such a giant billow is equivalent to a pressure of three tons per square foot.