16G 
years, and thereby arrive at the conclusion that the accumula- 
tion of the whole required 720,000 years/’ 
This somewhat long date, examined by Mr. Pengelly’s own 
standard, proves not nearly long enough. He has said (p. 24) 
that 250 years have failed to precipitate an amount of cal- 
careous matter sufficient to obliterate incisions which at first 
were probably not more than an eighth of an inch in depth. 
I have recently seen the cave under the courteous guidance 
of this gentleman, and was able to observe specially an in- 
cision to which he pointed our attention. It might seem 
to have ai'gued too much intrusive euriosity and too little confi- 
dence in our guide for me alone, amongst a large party of ladies 
and gentlemen, to have attempted too near a view ;but my belief 
is that the inscription is not nearly so deep nor the incrustation 
so great as above indicated. The example proves too much, 
and in all probability there has been no appreciable growth in 
any of the formations. In fact, the source of supply has from 
some cause failed almost entirely.* 
All this matter might easily have been illustrated by sinking 
a shaft downwards through from thirty to fifty feet of earth 
and rock, so as to ascertain the composition of the superincum- 
bent mass. This would have been a very easy and compara- 
tively inexpensive operation. Why has it not been attempted ? 
If twelve feet in thickness of stalagmite has been wasted by 
the rain, out of this thirty to fifty feet, it would be interesting 
to ascertain the state of the remaining limestone.! 
The specimen which has been sent to me probably exhibits 
this, and shows that whilst the hard rock is entirely impervious 
to water, the clefts and fissures are, on the contrary, perme- 
able, and the means of supplying the material for the stalagmite 
in the crystallized carbonate of lime visible in the specimen. 
* See Appendix A. 
| McEnery (p. 75) says, “ On a late occasion, the wood which clothed the 
cliff was partially cleared away ; the rock presented bare, bleached, and 
corroded surfaces. There was no large rent or external chasm observable 
on its summit. The only visible opening, except the two mouths, is through 
the cleft, which forms and extends inwardly from the southern mouth.” 
‘ ‘ The physical impossibility that the enormous mass of loam could have 
entered exclusively through the present mouths inclines us to think those 
canals open in the concealed 'mouths of the former entrances.” — McEnery, 
p. 113. 
“ On further examination, I found that the rocky cover of the cavern is 
perforated with numerous crevices or windows, partly choked with mud and 
brambles, through which, at so many port-holes, the mud in a state of fluidity 
may have entered into the common reservoir of the interior.” — McEnery, 
p. 281. 
