MEETINGS OF SOCIETIES. 583 
Dunedin Harbour, somewhere about 200 acres of reclamation have 
_ been executed, but several facts already alluded to in this paper, 
such as the reduction of the bar by natural forces alone, before 
dredging commenced; the identity of the average heights now 
and in Captain Stokes’ survey; and the clearing away of the 
inuer bar, all point to the conclusion that the diminution of 
tidal water has not had a prejudicial effect in any practicable 
degree. 
But if the reclamation is open to suspicion, the straightening 
and the deepening of the Victoria Channel must have had a 
powerfully beneficial effect in shortening the run in one part trom 
63 to 54 miles, and in giving a more uniform grade for the run 
of the tidal water. That this is of great importance will be mani- 
fest by a study of the conditions of the tides in the harbour. 
The high water at Dunedin rises on ordinary occasions to 
the same height as at the Heads, but not till 14 hours later. 
When, therefore, the water is at its height at the entrance to the 
harbour the water at Dunedin is from 1 to 2 feet lower, and there 
is a wedge of water wanted to completely fill the basin. If the 
time of travel to Dunedin be shortened, the difterence in height at 
the same moment will be less, and a gain in quantity of water will 
be the result. Thus the increased facilities given by the improve- 
ment of the Victoria Channel for the travel inwards of the tidal 
wave are compensation for the space taken up by reclamation, 
and we may calculate that if high water at Dunedin can be 
hastened by 10 to 15 minutes, and an average gain of one and a-fifth 
inch ot water over the whole Upper Harbour affected, the quantity 
of tidal water coming and going is not lessened by the works already 
carried out. 
Works for the improvement of the entrance must have two 
objects, these being the deepening of the bar and the straightening 
of the channel. There is no hope of effecting this latter part by 
dredging on the north spit, because that has been formed by the 
stream ‘choosing to cling to the opposite side, and it would still do 
so, and allow anaccumulation on the northern bank. The only 
manner in which a permanent improvement upon the bar and the 
channel can be obtained is by the use of a training wall to alter the 
course of the main current, and send it outwards ina line directly 
opposed to the heaping-up force of the ocean, instead of its being 
in a direction as at present inclined. This should start from the 
vegetation at high water mark, and go right across the north 
channel to the bar, thus forcing the water presently in that channel 
to go by the line of leading lights where it would pass into the 
ocean through a passage 2000 feet wide, instead of being dispersed 
as at present over a very wide area whereby its force is diffused 
and dissipated. The effect would be jincreased scour by the con- 
centration, and a removal of the sand until such a depth and 
cross section be attained as would allow the body of water to pass 
at a velocity less than that capable of moving that material. 
This contraction would not prevent the proper filling up of the har- 
bour, for the widthlavailable for the passage of the water would still be 
greater by 700 feet than that at Harrington Point by which the 
harbour is partly filled for the first half of the flood, while as the 
wall is proposed to be only up to halt-tide level, the second half of 
the flood would enter pretty much as it does at present. 
Sir John Coode proposes a second wall going from Taiaroa 
