Page:Popular Science Monthly Volume 72.djvu/243

This page has been proofread, but needs to be validated.

by the report of Captain Moore, R.N.,[1] who in 1888, in command of H. B. M. ship Rambler and two auxiliary craft, undertook a thorough survey of the river and estuary, which he continued in 1892, and whose vessels narrowly escaped total wreck.

The Birth of the Bore as shown by Observed Water Levels

In this survey observations of water-level were taken simultaneously at three places: Volcano Island, away out at the mouth of Hangchow

PSM V72 D243 River flooded by ten foot high tidal wave.png
Aspect of the River at the Same Place as the Last Picture, and Only Two Minutes Later. Wave Ten Feet High in the Center.

Bay; Rambler Island, fifty-one miles farther in; and Haining, twenty-six miles up the river. These measurements exhibit the nature of the bore very clearly. At 8:30 p. m. the water was one foot below mean level at Volcano Island, twelve feet below at Rambler Island and eight feet below at Haining. Thus the water sloped down from Haining outward to Rambler, and also downward from Volcano inward to Rambler; the water was running up the estuary toward Rambler Island, and down the river to the same point. By 9:30 there was no great change, but the water had risen two or three feet at Volcano Island and at Rambler Island. By 10 o'clock the level was rising rapidly at Rambler, so that there was a nearly uniform downward slope

  1. "Report on the Bore of the Tsien-Tang-Kiang," London, 1888. "Further Report," etc., 1803. Also, in Proceedings of the China Branch of the Royal Asiatic Society, 1888.