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Proceedings of the British Association. 



was formerly discussed, Mr. Russell had attributed these anomalies to 

 the great southern tide wave entering the Firth at a different period 

 from the great northern tide wave, to which the periods of high and 

 low water cn the east coast of Britain are principally due. But other 

 explanations had also been suggested in quarters so high as to entitle 

 them to great respect. For the purpose of settling this question, and, 

 if possible, reducing these anomalous tides to some law, Mr. Russell 

 had recently instituted second series of observations on the tides of the 

 Firth of Forth, conducted under very careful observers, the height of the 

 tide being observed simultaneously by different observers, at the different 

 stations, who recorded their observations every five minutes, and con- 

 tinued them unceasingly night and day. They had only as yet extend- 

 ed over a few weeks, but already there had come out of them results of 

 a decided character, so as to set at rest the question of the origin of 

 these tides, and to illustrate some curious points in the history of li- 

 teral tides. The tides already observed had, he thought, proved the 

 accuracy of the theory he had formerly advanced on this subject. But 

 it would still be desirable that these observations should be continued 

 and extended. He then proceeded to exhibit the results of the obser- 

 vations in a series of accurate diagrams of the tides : — 



This diagram represents the two successive tides of a day, as usually 

 observed on the coast of Britain. The line Ax, being on the level of a 

 given low water, is divided into equal portions, representing hours, mi- 

 nutes, &c, and lines perpendicular to Ax, namely, xy, XY, xy, propor- 

 tioned to the successive heights, so that Hj is high water in the 

 morning, H 2 is high water in the evening, Lj and L 2 being the suc- 

 ceeding low waters. In this case the tides exhibit the usual form, and 

 at the mouth of the Firth they are in tolerably close accordance with 

 it. In the upper parts of the Firth they deviate from it very widely, 

 as in the following diagram : — 



X 



A 



n 



'2 



