83 
of Edinburgh , Session 1884-85. 
walls at the Mersey, but without telling me why. My brother and 
myself had successfully improved eleven different navigable rivers 
by means of training walls and dredging. There was not one 
physical characteristic of the Mersey which, viewed by itself, would 
render inapplicable the same treatment, and it had not yet occurred 
to me that certain characteristics, any one of which was harmless in 
itself, might, when taken together, justify fears of disaster ; so 
that it was not until I had resurveyed three of the rivers I had 
formerly improved on the system of training walls that I con- 
cluded it was solely due to the existence of certain character- 
istics which existed in all the three rivers, that the deposits of 
sand had so quickly followed the erection of the training walls. 
Hence I concluded that it would be unsafe to risk training walls in 
the Mersey, where similar characteristics were not only more 
numerous, but much more strongly marked. 
The river Lune was the navigation that first startled me. It was 
improved by training walls and by steam dredging of the channel, 
with an eye solely to improving the navigation, and with no after- 
thought of reclaiming land by accretion. The walls were but 3 feet 
high, and placed strictly parallel to the stream, nor was any part 
protected, still less enclosed, by cross walls. Two years after the 
completion of the work, however, it was found that a considerable 
accretion of sand had taken place. In 1851, being only two 
years after the works were finished, a marine survey was made, 
which showed that the amount of accretion behind the walls had 
already amounted to 3000 cubic yards of sand, although that amount 
of deposit was quite balanced by a gain of additional water admitted 
from the sea through the deepened channel. In 1884, however, 
thirty-four years after the conviction of the works, I had the Lane 
once more surveyed, when it was found that 230 acres were covered 
with grass, thus establishing the important physical fact that the 
deposit had risen to the level of high-water neap tides, and the total 
accretion had reached the amount of 5,536,060 cubic yards. In the 
same year I had a fresh survey taken of the river Mth below Dum- 
fries, — a navigation which had been improved by training walls 
alone, — and the accretion was found to amount to 3,192,970 cubic 
yards ; and again, in the same year, I revisited the third river, to 
which I have referred, — the Kibble below Preston,' — and found that 
about 5000 acres of what was formerly estuary were grassed over. 
