Reviews—Daubrée’s Subterranean Waters. 30 
of the author by way of showing how it can make its way against a 
powerful pressure of steam. This has an important effect in the 
general mechanism of infiltration (vol. ii. p. 214), and helps to over- 
come the obvious difficulty with respect to water circulating in open 
fissures, which would appear liable to be forced back by pressure 
from within. 
After giving a description of the permeable and impermeable rocks, 
the author discusses the phenomena in connection with the more 
superficial sheets of water, such as have no impermeable bed above 
them. Having rather a partiality for Greek compounds, he 
designates this ‘ Phreatic Water.” The water-line, or upper level 
of this sheet, ranges from a few feet to 100 métres or more. This 
« Phreatic,” or well-water, is largely distributed throughout Drift 
beds (Terrains de transport), and many plans and sections are given 
showing its “régime” in different towns of Europe. He quotes 
from Prestwich’s address to the Geological Society (1872) with 
reference to the water-bearing gravels of London which repose on 
an impermeable clay, and relates how that, before the great water 
companies furnished an independent supply, the metropolitan popula- 
tion was largely confined to the water-bearing gravels. Curiously 
enough, in order to illustrate this, a section is given of the aquiferous 
gravels at Oxford resting on the Oxford Clay. Not the least interest- 
ing account of the superficial sheet of underground water is that 
relating to the Fontanili of Lombardy, illustrated as usual by small 
plans and sections. The inhabitants of the favoured district are in 
the habit of knocking out the bottom of a tall cask, and placing it in an 
aquiferous bed, some two or three metres below the surface, when 
the pressure raises the water in the shaft or funnel thus formed, and 
a notch being cut in the upper rim, the surplus water is thus con- 
ducted into channels of irrigation, much on the principle of water 
meadows in the South of England. The water-bearing strata of 
Lombardy above referred to occur in the gravels and sands of old 
and modern alluvions, and the water which they contain percolates 
towards the great rivers to such an extent as to restore to these the 
water of which the numerous irrigation canals had deprived them. 
The “ Phreatic Water” is by no means confined to the Drift, as of 
course beds of Tertiary, Cretaceous, Jurassic age, etc., contribute 
their quota when these occupy the surface of a country. Under this 
heading some interesting details are given of the well-water of Paris, 
which, it appears, is contained partly in the alluvium and partly 
in permeable Tertiary beds upheld by the Plastic Clay. Since M. 
Daubrée has so extremely enriched his work with plans, sections, 
photographs, ete., a section across the valley of the Seine at Paris in 
illustration of these interesting details would have helped the reader, 
who is not a little puzzled to find a plan apparently of the alluvial 
deposits near Paris immediately under the heading “terrains tertiaires 
des départements de la Seine, etc.” 
The results of contact between permeable and impermeable rocks 
are next discussed. The contact may be the result of simple strati- 
fication, as when sands or gravels overlie clay. The section at 
