26 ON THE REMOVAL OF BARS FROM 
which he referred was that of the tidal and river scour. He 
might say that that theory, now thirty years old, had been fully 
confirmed by his subsequent experienc. * * * * It wa 
further known that those bars were always worst after a pre- 
valence of on-shore wind and heavy sea, and were best when the 
river was in flood. * * * * The waves were the true ‘de- 
positors’ of the bar, the river was only an ‘excavator,’ and there 
would still be all the phenomena of a bar at the mouths of estu- 
aries, although the river water did not bring down a single particle 
of suspended matter. ni If his bar theory, as applic- 
able to tidal rivers, was right, it clearly followed that, if the pier 
heads were carried into water of sufficient depth to prevent the 
as d 
3 
z. 
ee 
Z 
5 
¢ 
5 
3:—* “With reference to the bar at 
sand of which the bottom of the bay is composed; the lower 
stratum of the water becomes therefore surcharged with sand, 
which is carried along by the tidal current.” 
Sir John Coode, remarking on the formation of bars, says :— 
3 «They were formed almost entirely by the sea, some rivers 
illustrating this in Australia. At the Swan River, on the coast 
Western Australia, facing the Southern Ocean, with very little 
tide, there was a bar of the worst possible description ; while the 
arra, at Melbourne, which discharged into a sheltered embay- 
ment at the head of Port Phillip, though it had a rise of tide pre- 
cisely the same as the Swan River (about 2 feet), had no bar, 
simply because it was in a sheltered position, and there was no — 
1 Minutes, Inst. C.E., vol. xxxvi, p. 236. 
2 “ Engineerin g yy, 1 
08. 
3 Minutes, Inst. C.E., vol. viii, p. 130. 
