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2. On the Physical and Scottish Statutory Limits of Sea and 

 River, as applicable to Salmon Fisheries. By Dr Fleming. 



Dr Fleming directed the attention of the Society, in the first in- 

 stance, to the characteristic features of sea and river proper ; and 

 then proceeded to consider the peculiarities of that common space, 

 alternately sea and river, to which he restricted the term estuary. 

 Ho then considered the nature of the space between high and low 

 water, and pointed out the mean level, or mid-tide mark, as the only 

 constant and universally applicable boundary plane. The influ- 

 ence of the tidal wave in reversing the current, checking the velocity, 

 and increasing the depth of the river, was next brought under notice, 

 and an experiment exhibited, illustrating the conservation of force, 

 which causes the waters at the head of an estuary, and the connect- 

 ed river, in certain circumstances, to attain a higher level than tho 

 high-water mark of the neighbouring sea-shore. He then coubidercd, 

 successively, the tests which, on different occasions, had been proposed 

 and employed ; viz. — point of stagnation ; presence of sea or river 

 water ; tho growth of sea-weeds ; fauces terras ; deltas and bars ; and 

 pointed out their usclessness in determining the physical limit between 

 sea and river. 



