26 
THE TANGANYIKA PROBLEM. 
suggests that some change in the sea must have taken place. 
In consequence of this it is incumbent on us to inquire 
whether there are other grounds for believing that the sea 
has become and is becoming steadily more salt. 
Turning to this matter we find that the subject has 
already been considered, but in general from other aspects 
than that which immediately concerns us at the present 
time. Thus, within the last few years we find both Jolly 
and others considering the increase of salinity of the ocean, 
and taking its existence for granted as a means in an 
attempt to ascertain the age of the earth. That the saline 
matters in the sea have changed in composition and in- 
creased in amount seems, indeed, almost indisputable from 
a variety of considerations. Thus Jolly points out that 
numerous analyses of the rocks of different ages show a 
marked contrast in the amount of common salt which they 
contain, the older the rocks the more the salt, and, further, 
that the percentage lost in the more recent deposits is 
matched bv the amount of salt dissolved in the water of 
j 
the present sea. Jolly also comes to the conclusion, and 
apparently with good reason, that the amount of salt which 
has been again lost by the sea, in the formation of rock- 
salt deposits, is to be considered as infinitesimal and 
negligible. 
Indeed, the same results would be forced upon us, if we 
were to apply the experience we have gained in the study 
of fresh and salt water lakes to the study of the sea itself. 
We find that where lakes have an outflow they remain 
fresh, because the salt which is brought into them is 
always being carried away by this outflow, but in lakes 
which have no outflow the modicum of salt which the 
rivers bring down remains in the water of the lake, so 
that it becomes more and more saturated until finally the 
