NATURE AND MAN IN THE FORTH VALLEY. 85 
the salmon cruives at Craigforth Mill, about three miles 
above Stirling. The rise and fall at the salmon dykes are 
very decided, at least ten feet in vertical height. Previous 
to the construction of the dykes, the limit of the tide would 
be a ledge of Old Red Sandstone rock which appears in 
the river bed a few yards higher up. There must have 
been a fine natural fall here, as now there is a fine artificial 
fall, the river being large and the volume of water great. 
But for this interruption the tide would rise for a great 
many miles farther west. I have never been able to find 
any trace of a tidal bore in the river. If there is such 
farther down the estuary, it has disappeared long before 
reaching Stirling. This is probably due to the irregular 
outline of both the northern and southern shores of the 
Firth, and especially to the narrow strait at Queensferry. 
There is, however, one peculiarity in the motion of the tide, 
long since observed, and which I have never seen satis- 
factorily explained, Sir Robert Sibbald, in his History of 
fife and Kinross published in 1710, puts it thus:—“ In 
Forth there are, besides the regular Ebbs and Flows, several 
irregular motions, which the Commons betwixt Alloa and 
Culross (who have most diligently observed them) call 
the Lakies of Forth; by which name they express these 
odd motions of the River, when it ebbs and flows: For 
when it floweth sometime before it be full sea, it inter- 
mitteth and ebbs for some considerable time, and after filleth 
till it be full sea; and on the contrary, when the sea is 
ebbing, before the low water, it intermits and fills for some 
considerable time, and after, ebbs till it be low water. And 
this is called a Laikie.” 
The phenomenon is probably caused, in some unexplained 
way, by the struggle between the river current and the tide 
—a struggle which is productive of many other peculiar 
phenomena. The rising tide being confined in the wedge 
of the estuary, becomes, by a well-known law, a current, 
and twice a day at Stirling may be seen the apparently 
strange occurrence of a river flowing swiftly the wrong way. 
The winding nature of the river course between Alloa and 
Stirling increases the effect of the tide. The tide used to 
flow up the River Carron for several miles, but the river 
