512 JUNCTION OF THE FRESH WATER OF RIVERS 
which it counterbalances ; and this, independent of the pro- 
gressive motion of the tide in the river. 
If the view which we have taken of this subject, in reference 
to the progress of the salt water, be considered as just, it will 
enable us to explain some of the phenomena of nature, at pre- 
sent rather perplexing, and may even be useful in its practical 
application. 
In examining the vegetable productions of the banks of ri- 
vers, at their junction with the sea, we are sometimes surpri- 
ed to witness the growth of plants, considered as the natural 
inhabitants of the sea-shore. But our surprise will cease when 
we reflect, that the sea-water proceeds farther up the river at 
every flood-tide than the sensible qualities of the water at the 
surface indicate ; so that the plants, which we hastily conclude 
to be out of the reach of the salt-water, are still within the 
sphere of its influence. Thus, at the Beach of Flisk, and even 
farther up the river, the Fucus vesiculosus, (the species commone 
ly cut for making kelp) not only vegetates, but in its season 
appears in fructification. 
But that which proves in a still more decisive manner, the 
action of the inferior stratum of salt-water at the place, is the 
growth of the coralline termed T'ubularia ramosa (Exx1s’s Co- 
rallines, Tab. xv. fig. A.), and another of a different genus, 
closely resembling the Sertularia gelatinosa of Pattas. There 
are likewise some traces of Flustre. 
A knowledge of the facts which we have already stated, may 
be of use to those who are engaged in the erection of salt- 
works at the mouths of rivers. In such situations, the open- 
ings of the pipes for obtaining the salt water, should be placed 
as near the bottom, or as deep in the water as possible; and 
water ought only to be drawn during the height of flood-tide, 
when the fresh-water is diffused over the surface. 
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