88 
Proceedings of the Poyal Society 
There is a depth of 20 fathoms at low water where the Clyde 
joins the sea, which is land-locked and sheltered, while there is only 
1 \ fathom at low water on the bar at the Mersey, which is in the 
open and stormy Irish Channel. 
In short, no two sandy rivers can w T ell be more different in their 
main features than the Mersey and the Clyde. It is therefore quite 
what might be expected, that there should be scarcely any accretion 
in the Clyde. 
The Tyne . — At the Tyne matters are, on the whole, in much the 
same state as at the Clyde, for the rise of tide is only 1.3 feet. 
There is uo bore, and the bar has been deepened and sheltered by 
the extensive breakwaters now in progress ; and though there are 
training walls, they have been erected so close to the land as to 
leave no large receptacle for silt to be deposited, so that there is 
hardly any similarity between the Tyne and the Mersey. 
The Tees . — As at the Tyne, the best means have in the case of the 
Tees been already employed of counteracting the risk of silting by 
the extension of the training walls down to the sea, and the erection 
of sheltering breakwaters which protect the bar, where there used 
to be only 3 feet of depth, whereas there is now a depth of 20 feet ; 
and, besides, there is only 15 feet of a rise of tide, with a flood tide 
current of only 4J miles an hour, so that no argument applicable to 
the Mersey can be derived from the Tees, any more than from the 
Clyde or the Tyne. 
From these rivers we turn to the facts relating to those in which 
silting has really taken place, and where training walls have been 
adopted, but where there are dangerous characteristics, but those of 
a comparatively subdued nature compared with those which are in 
the Mersey. 
The results of the statements already made may be thus shortly 
summarised. That silting up to grass level may take place in an 
estuary, though the rise of tide may be no greater than 24 feet, 
as at the Kibble ; where there is no bore, as at the Lune and 
Kibble ; where there is no bar, as at the Nith; and where the ratio 
of matter in mechanical suspension may be as low as 3'68 cubic 
inches, as at the USTith. 
It is obvious, therefore, that there is every possible reason to 
expect that if walls be erected accretion will take place up to the 
