199 
must indicate an enormous length of time, inasmuch as the 
stalagmitic floor cannot be formed faster than the limestone 
is dissolved overhead, and the solution of that limestone is 
due to the presence of carbonic acid, and there is no possi- 
bility, under existing conditions, of any other water entering 
that cavern than what falls on the hills as rain. I do not ask 
you to take the thickness of the stalagmite as a chronometer, 
but will tell you a fact. There is in one part of the cavern a 
high boss of stalagmite rising up from the floor. That boss 
betokens that its formation was comparatively very rapid. 
Take that rapid rate as the measure. ‘There ison the boss an 
inscription :—‘ Robert Hedges, of Ireland, Feb. 20, 1688.’ 
For 184 years the drip has been going on, and it has failed 
to obliterate that inscription. The film of stalagmite which 
has accreted on it is not more than the twentieth of an inch 
in thickness. Nearly 200 years for the twentieth of an inch, 
and you have 5 feet to account for! But whatever may have 
been the time necessary for the formation of the stalagmite, 
the cave-earth is older still. There is another and more 
ancient stalagmite, thicker still; below that there is another 
deposit older than all, and in that we find human imple- 
ments.”’ 
Now, what is the sum of these periods in the stalagmitic 
chronometer? Let us see: At starting, there are 184 years 
for 1-20th of an inch of the boss, or 3,680 years for one 
inch, and this + 60, the number of inches deposited, gives 
us no less a period than 220,811 years for the whole deposit. 
To this period must be added some thousands of years for the 
deposition of the cave earth, and then for the five feet of 
underlying stalagmite another 220,800 years. ‘hen another 
layer of earth, and another layer of stalagmite, in some 
places 12 feet thick, which, at the same rate of deposit, 
would require about 528,820, and to this again must be added 
some thousands of years for the formation of the breccia, 
which les at the bottom of all. Putting these periods 
together, we have 2,000 + 220,800 + (say) 2,000 + 525,820 
+ 2,000, or 976,420 years as the time since man first used 
this particular cavern. 
It will at once be seen that the validity of the argument 
drawn from these deposits as to the antiquity of man stands 
upon the assumption that the rate of the deposition has been 
the same in all ages. Now, if the rate of deposit has been 
the same, the conditions must have been the same ; but what 
proof is there that this has been the case? According to some 
authorities, we are led to conclude that Kent’s Cavern has not 
