196 



THE GEOLOGIST. 



manifest to us the internal activity of our globe, immense bodies of 

 water, in the form of vapour, are disengaged. 



" One naturally asks if the supply of this water is not kept up 

 partially, at least, from the surface, and, if so, by what means ? 



" It is difficult to imagine this supply produced by a free circula- 

 tion ; for the way open to the descending water would form a means 

 of escape which would naturally offer itself to the ascending vapour. 

 Now the immense pressure of this vapour in the volcanic districts — 

 a pressure great enough to force columns of lava, about three times 

 denser than water, to vast height's above the sea -level — proves that 

 these safety-valves do not exist. 



" I have therefore been led to examine whether the water cannot 

 penetrate into these deep and hot reservoirs, not by fissures as pre- 

 viously imagined, but in virtue of the porosity and capillarity of the 

 intervening beds." 



M. Daubree then refers to the experiments carried on by M. Jamin, 

 showing the influence of capillary attraction in changing the condi- 

 tions of equilibrium between different pressures by means of a column 

 of liquid, and points out that the geological problem requires a 

 variation in the temperature not introduced by M. Jamin, — in fact 

 the liquid in one part of the connecting column must be reduced to a 

 state of vapour, in which, perhaps, it will be governed by different 

 laws. 



M. Daubree then proceeds to describe his apparatus as follows : — 



" I have therefore constructed an arrangement, of which the prin- 

 cipal end is to join — by means of a partition of porous sandstone of a 

 fine close grain — on one side a closed chamber, in which the pressure 

 of the steam=one seven-eighth atmospheres, and on the other a space 

 in direct communication with the external air, half filled with water, 

 which soon was heated to the boiling point : in the latter chamber — 

 of course, being open to the atmosphere — the ordinary pressure was 

 not exceeded, although the thickness of the sandstone partition was 

 but two centimetres. The result of the experiment proves that the 

 water is not driven back by the counter-pressure of the vapour : the 

 difference of the pressure on both sides of the partition does not 

 prevent the liquid from penetrating from the region comparatively 

 cold to the region comparatively hot, by a kind of capillary attraction ; 

 favoured also by the rapid evaporation going on in the latter." 



M. Daubree promises further experiments with a thicker partition, 

 which will enable the vapour in the first chamber to be raised to a 

 higher temperature. 



The results he has already arrived at prove that capillary attraction, 

 in addition to weight, can — in spite of very strong interior counter- 

 pressure — force water to penetrate from the superficial and cold 

 regions of the globe into the interior, where, by reason of high the 

 temperature and pressure, it, in the shape of steam, is capable of 

 producing great mechanical and chemical results. 



" Do not the foregoing experiments," asks M. Daubree, " also make 

 us acquainted with the main-spring of volcanic action and of other 



