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PACIFIC SCIENCE, VoL XI, April, 1957 
by the balance between salt and fresh water. 
He wrote, "The water-bearing stratum is the 
lava of the volcanic dome as it was finally 
completed by the upbuilding volcanic forces. 
The water-bearing lava rock is covered with a 
layer of clay, the product of decomposition 
of lava, which in turn, is covered with a stra- 
tum of coral rock, formed as a fringing reef, 
above which strata of coral and volcanic ma- 
terial may alternate. The depth below sea level 
to which the retaining clay stratum would 
need to extend in order that fresh water in 
wells should be raised forty-two feet above 
sea level by the hydrostatic pressure of sea 
water of density 1.026, is 1614 feet, which is 
but little deeper than the depths at which clay 
was found in the deeper wells." (The 1.026 
specific gravity for sea water would give a 
ratio of 38.5 between the depth to sea water 
and the height of fresh water: 1.000/0.026 = 
38.46.) 
"An arrangement of coral and clay strata 
such as here presented fully accounts for the 
phenomenon of flowing wells on an island of 
volcanic origin. The lava of the volcanic dome 
is somewhat porous, penetrated by cracks, 
and open enough to permit the movement of 
water; the clay stratum overlying the lava 
prevents the escape of water upward; the re- 
maining coral and clay strata simply add an 
overlying mass, and the elevation of the up- 
permost coral layer above sea level, lined as it 
is by clay, raises the sutface of the underground 
water accumulations until they escape as 
springs over the coral brim, or rise above sea 
level in artesian wells to the height of escape." 
Thus it appears clear that Andrews, who had 
no knowledge of the work done in Europe on 
coastal ground waters, entirely independently 
worked out what we now call the "Herzberg 
Principle." On Dec. 24, 1955, I called on 
Professor Andrews and we discussed the mat- 
ter at some length. Apropos of statements 
sometimes made that Andrews got his ideas 
from the Alexanders (plural), he told me that 
Arthur C. Alexander merely transmitted his 
father’s idea that sea water exerted a pressure. 
Working out mathematically the ratio of the 
depth to salt water to the height of the water 
table, as a function of the relative densities 
of the two liquids was entirely Andrews’ idea. 
Thus Professor Andrews seems clearly to be 
the first American to give a mathematical 
expression of the ratio. 
Andrews’ remarkable insight into the phe- 
nomena is also shown by his correctly ex- 
plaining the so-called "clay," which acts as 
the restraining member, as the impermeable 
residual matter due to very advanced weather- 
ing in place of the upper or outer parts of the 
body of lavas. Others had thought that the 
clay originated as some sort of marine sedi- 
ment at a time when the sea reached higher 
on the island. It is hard to think that clay, in 
water, would remain in place on steep sub- 
marine slopes. 
It is most unfortunate that Andrews’ paper 
was never printed, for in its typescript form 
it gained only moderate circulation. 
In 1908 Gregory and Ellis described fluc- 
tuations of water levels in wells near the 
Connecticut shore, but did not refer to the 
density of sea water. They reported one well 
in Norwalk that had fresh water to a depth of 
50 or 60 feet in sand, but only salt water at 
lower levels. Plugging of the bottom of the 
well shut off the salt water successfully. 
Clapp, also in 1909, reported on conditions 
in southern Maine, where salt water had been 
found under fresh water in a good many wells 
near the shore, but he made no mention of 
the density of sea water. A typical well in 
Islesboro, "obtained good water at 181 feet 
from the surface, but drilling continued, and 
at 220 feet salt water was encountered. The 
well was filled with Portland cement to a 
depth of about 200 feet from the top, the sea 
water being thus shut off, and the water was 
reported of good quality in 1906." 
Hitchcock, in 1910, in an address to a 
Special Conservation Meeting held in Iolani 
Palace, told of the lava rock aquifer and the 
cap rock of the artesian system. He made 
some use of Alexander’s idea of the pressure 
