British Association. 219 
region of violent earthquakes or of active or extinct volcanos. The 
historical evidences of Saxon and Roman occupation were then 
briefly alluded to, especially the coins, pavements, monuments, and 
- temples of the imperial troops and rich colonists from Rome sojourn- 
ing at ‘Aque Solis’ for some 300 years. Then, as now, and probably 
long before, the hot-springs here, as at Aix-la-Chapelle, Baden- 
Baden, Naples, Auvergne, and the Pyrenees, had a persistent tem- 
perature, constant volume, and identity of mineral ingredients (as 
remarked by Daubeny), though exceptions have at times occurred, 
especially with earthquakes. ‘How long has this uniformity pre- 
vailed ? Are the springs really ancient in reference to the earth's 
history; or, like the course of the present rivers and the actual shape 
of our hills and valleys, are they only of high antiquity when con- 
trasted with the brief space of human annals? May they not be 
like Vesuvius and Etna, which, although they have been adding to 
their flanks, in the course of the last 2000 years, many a stream of 
lava and shower of ashes, were still mountains very much the same 
as they now are in height and dimensions from the earliest times to 
which we can trace back their existence? Yet, although their foun- 
dations are tens of thousands of years old, they were laid at an era 
when the Mediterranean was already inhabited by the same species 
of marine shells as those with which it is now peopled; so that those 
volcanos must be regarded as things of yesterday in the geological 
calendar !’ 
Thermal waters in the Pyrenees, Alps, and elsewhere spring forth 
along great rents in the earth’s crust; just as volcanos, active and 
extinct, have burst out on similar great lines of fissure; hot springs 
and emanations of gas and steam abound, too, ‘in regions where vol- 
canic eruptions still occur from time to time ;’ and where the fiery 
energy has ceased, as among the extinct volcanos of Eifel and 
Auvergne, such springs exist, and, like the rain-furrowed cones and 
river-worn lava-streams, ‘indicate that the internal fires have become 
dormant in comparatively modern times.’ 
Thus connected with volcanic phenomena, the issue of thermal 
waters is comparable with ‘the vast clouds of aqueous vapour 
which are copiously evolved for days, sometimes for weeks, in suc- 
cession, from craters during an eruption.’ Their power, too, of 
raising solid matter, and of transferring gases from the interior to 
the surface, ‘is far more considerable than is commonly imagined. .. . 
Professor Ramsay has calculated that if the sulphates of lime and 
soda, and the chlorides of sodium and magnesium, and the other 
mineral ingredients that the Bath Waters contain, were solidified, 
they would form in one year a square column nine feet in diameter, 
and no less than 140 feet in height.’ According to Daubeny, 250 
cubic feet of nitrogen, besides carbonic-acid, is evolved daily from 
these waters. Both of these gases escape freely also from volcanos. 
The former may be derived largely from the nitrogen of atmospheric 
air carried down by percolating rain-water, and deoxidated at great 
depths, as well as to some extent from organic matter in the rocks. 
‘If we adopt the theory already alluded to, that the nitrogen is 
