416 
Geyser it was found that the boiling-point rose from 210° at the surface, to 278° at the 
depth of seventy-seven feet. This ratio, giving a rise of the boiling-point of 68 
in seventy-seven feet, would make the boiling-point of water at seven thousand one 
hundred feet not 212°, but 6,366° (and that merely under the pressure of a column 
of water, while the pressure of a column of rock would be about two and a-half 
times as much). These astonishing figures prove that the ratio of the rise in the 
boiling-point being higher than the ratio of the increase of the earth's temperature 
with depth, water ivould never be raised to boiling-point by the internal heat of the earth 
alone. 
At the same time, though water would not boil from the internal heat of the 
earth, yet where it exists beneath seven thousand one hundred feet it must always 
have a temperature above 212°. Immediately upon the production of an outlet, 
whether by natural means, such as a fault or earthquake fissure, or by artificial means, 
such as a bore, the relief of pressure would bring about a rise of the water in the fault, 
fissure, or borehole analogous to that of the rise of the mercury in the tube of a 
thermometer. 
In the case of a thermal spring it is not necessary that the fissure should be open 
down to a depth of seven thousand one hundred feet, as the requisite high temperature 
may be found when the water is in contact with subterraneous igneous rocks still 
retaining much of their original heat. 
In the artesian wells of our Western Interior, the water issues at temperatures 
which are high, although still far below boiling-point — e.g., Back Creek 70°, Aramac 
Private Bore No. 1, 81°, Muckadilla 124°, Barcaldine 102°, Saltern Creek Government 
Bore 115°, Saltern Creek Private Boro No. 3, 128°, Blackall 119°, Tambo 98°, Cunna- 
mulla 106°, Charleville 106°, Manfred Downs No. 2, 110°, No. 10, 118°. 
There are, as already mentioned, few records of the strata passed through, but at 
all events there is nothing to show that any igneous rocks whatever have been met with 
in the bores. The high temperature of the water may be taken to be the result solely 
of the internal heat of the earth. It will, however, be observed that the temperature 
of the water does not bear a constant relation to the depth. The internal heat must, 
therefore, have affected the temperature of the water elsewhere than in the ])laee3 
where the water has been tapped. 
Now, although the temperature of the water of the artesian wells is somewhat 
high, the depth at tvhich it has been struck is in no case great enough to account for tt- 
Por example, the temperature, of 119° attained at 1,663 feet in the Blackall Bore 
would not be reached by the rock before the bore had been carried to the depth of 2,450 
feet, assuming that the constant surface temperature is 70°, and the increase with depth 
one degree in fifty feet. The water, I take it, must have reached, with the undulations 
of the permeable strata containing it, lower depths than those at which it has been tappd 
by the bores. This is to my mind a confirmation of the view I have always held, that the 
Boiling Downs strata undulate considerably. 
The commonly accepted theory of artesian wells is that a permeable stratuin> 
with impermeable strata both above and below, carries water from its outcrop down to 
whatever depth it may be buried beneath accumulations of later date, and that on tapping 
the water-charged stratum the water will rise to, or near, the level of the outcrop of the 
stratum. Till lately I have rigorously adhered to this theory, which perfectly accounts 
for many of the best-known artesian wells of Europe and America, but in the case of 
the Queensland wells it is doubtful if the strata in which the water has been tapped 
crop out at elevations sufficient to give the pressure required to raise the water to the 
surface. 
