94 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the coalescence of disengaged gas bubbles and if the material be 
not too thick, the coalescence of the vesicles into observed vertical 
streams maybe observed. When, however, we endeavor to imagine 
what takes place in a mass of unconsolidated rock, it may well be 
questioned whether the observations above noted supply us with a 
fair example of what takes place, for the reason that the fluid, as 
above remarked, is but a small part of the mass of the strata. On 
this point we may clear our minds by certain other facts which are 
well known, or by experiments which are easily made. 
In the case of gas wells the field observations make it evident that 
the gas passes through the rock, which may be compact sandstone, 
with considerable rapidity and for a distance of many hundred or, it 
may be, some thousands of feet on either side of the artificial shaft. 
In oil wells, as well as in the greater part of the so-called artesian 
wells, it is the passage of this gas, which is probably in the vesicular 
form, along with the water to the shaft that is the effective agent in 
causing the flow to the vent. It is thus made evident that the lateral 
flow of gas through the rocks which have the unconsolidated char¬ 
acter of those in which the earthquake fountains are formed may 
fitly be assumed. The question now arises whether the upward 
shafting phenomenon which is so evident in the escape of gas in an 
undivided body of fluid will take place when the fluid is contained in 
the small, imperfectly connected cavities of rocks in which the 
channels leading to the fountains are formed, and whether a sudden 
movement of the earth, in a jarring manner, is likely to bring about 
this action. On this point neither observation nor experiment gives 
us much information. There are, however, certain facts at our com¬ 
mand which are not without value. 
In rocks, even those which are as little consolidated as the clays 
and sands of the last glacial epoch as they are exhibited in New 
England, more or less developed joint planes are of common if not 
universal occurrence. That these joints are open enough to permit 
the lodgment or the passage of water is shown by the fact, that when 
formed in clay they often may be seen to have afforded the way to 
ferruginous waters in a downward course. It is likely that these 
joints afford the place of beginning of the accumulations of upgoing 
gases which are to break their way to the surface. The result of a 
shock of sufficient severity would doubtless be to convert a quantity 
of the previously dissolved gas into the state of separated vesicles 
which would tend to urge their way through the crevices and to 
