The Tides. 223 



the one we have followed thus far. Bat where is our associate? 

 While we were liugering in the channel, and the straits, he went 

 around the longer way with great strides and met our predecessor 

 at the point where we now are, just as we were tasting of the Dutch 

 Rhine, and combining with him made the passage of the Skagger 

 Rack and washed the shores of Grotheborg Sweden at 30 hours as 

 we shall when -i2 hours old. From Cape Clear the tide moves 

 along the west shore of Ireland, the Western Isles and coast of 

 Scotland, reaching the Orkney and Shetland Isles at the 2 1st 

 hour. Here it divides, never to meet again ; one part passes be- 

 tween the Islands and moves south along the coast of Scotland 

 and England and at the mouth of the Thames at the 36th hour 

 passes a Channel tide 2-1 hours old, its own associate is already 

 approaching Jutland. The tide between the Shetlands and Nor- 

 way moves rapidly southeastward through a belt of water over 

 100 fathoms deep, and at the 26th hour meets a channel tide 12 

 hours older, as we have before observed. When this Norway 

 tide departs eastward a portion breaks to the westward and fol- 

 lows the main wave along the coast of Scotland, but, being de- 

 layed by several hours, causes a second high water, thus making 

 apparent four highwaters as far as Peter Head. These four tides 

 were attributed to the channel tides, but it is evident that if this 

 was the case, the tides would be observed along the Eng'ish rather 

 than the Scottish coast. The middle of the North Sea has no tide, 

 which is corroborated by careful soundings made by the Bdtish 

 navy over a shoal where no oscillation was observed. Froni this 

 it will be observed that there can be not less than two tidal waves 

 in the North Sea at any time, and as many as four at one time 

 during each phase, the resulting confusion of currents can easier 

 be imagined than described. 



A portion of the tide which we have been considering enters 

 St. George's and Bristol channels, also the INorth channel into the 

 Irish sea. The waves by St. G-eorge's and North channels meet 

 near the the Isle of Man about the 23d hour, their range along 

 the Irish coast was moderate, but the meeting produces a range of 

 20 feet and over. 



The tide in the Bristol channel, charging straight from the sea 



