434 T. W. E. DAVID. 
the water-bearing stratum be regarded as more or less collapsible 
or sponge-like. Were the water-pressure hydrostatic, it is interest- 
ing to notice that, assuming a density of 2:5 for the overlying 
strata a depth equal to two-thirds of the elevation of the point of 
intake above the general surface in the vicinity of the wells would 
be supported. For example, an elevation of 1,000 feet above the 
general level would give at a depth of six hundred and sixty-seven 
feet a pressure (forty-six and a-half tons to the square foot), equal 
to the weight of the overlying stratum. At less depths, the head 
ought to raise the surface till an equilibrium was established 
through the inflow into the stratum and the consequent reduction 
of the head. Im all cases however, with a collapsible stratum, 
the weight of the overlying strata will serve to maintain the 
artesian flow, until the point of maximum consolidation is reached, 
and that too, whether the head be hydrostatic or hydraulic. 
Mr. H. C. Russet remarked that he had understood Mr. Gipps 
to say, that the origin of our artesian water was an old fresh-water 
sea, which by the action of hot ‘springs on its shores had been 
slowly covered over with a layer of silica, and that this supported 
the denuded gravel and soil carried down to the sea by rain-water 
until the present strata overlying the water was formed, and 
pressing on the water caused it to rise in bores artificially made. 
He could not understand how this was possible, for it had been 
proved that the water beds extended hundreds of miles, and Mr. 
Gipps’ theory obliged us to assume that the hot springs had covered 
this enormous area with a deposit of silica, thick enough to carry 
the gravel and other matter carried down by the rains on to it, 
which deposits would be very thick at the rivers and very little 
in other places. The theory seemed to him contrary to all experi- 
ence, and also to what one would expect from the laws governing 
such deposits, and he therefore could not accept Mr. Gipps’ view 
of the origin of our artesian water. 
Mr. J. W. Grimsuaw did not consider that Capt. Gipps had 
given them any information which would justify them in discard- 
ing the theory of the hydrostatic pressure of artesian water. The 
