427 
of Edinburgh^ Session 1864 - 65 . 
the Engineers,* when he was superintending the excavations in 
Bermuda for the dockyard, found the eggs and bones of a sea-fowl, 
one of the existing species which lays its eggs in crevices of the 
rocks, entombed in the coarse limestone rock. The poor bird, 
whilst sitting on its nest, had been caught by some storm of sand 
which filled up the crevice, and the prisoner, with its eggs, became 
petrified and encased in the rock. Many examples of the same 
kind had come to Lieut. Nelson’s knowledge. He found a canister- 
shot and a gold knee-buckle similarly fossilised. Wherever the 
limestone rock has been exposed to the weather, it gets encrusted 
with crystallised stalagtitic matter, so that in any place where a 
hollow or trough occurs on the surface of the rock, water falling 
or flowing into it, stands. In these circumstances it is not difficult 
to see how water, filtering at first through to the roof of a cave, 
might, in the course of time, have its course diverted from the spot 
where it used to drop abundantly, or at all events, how it should 
diminish in quantity. It is therefore reasonable to infer, that in 
the early history of the caves, the water flowed through the roofs 
much more copiously than afterwards. The cracks and interstices 
in the porous rock would become gradually filled up, so as to cut 
off or curtail the flow of water, and consequently lessen the supply 
of calcareous precipitate. 
On these grounds the author entirely repudiated the notion that 
this stalagmite had taken the enormous period to grow, indicated 
by the foregoing calculation, — though what period it actually did 
take, there were no data to determine. 
In concluding, the author referred to the probable origin of these 
caves. He considered that they had originally consisted of great 
masses of loose sand which had become enveloped in compact lime- 
stone. Lieut. Nelson, in his paper describing the excavations for 
the dockyard, mentioned that “ the irregular density of the rock 
is exhibited on all scales, from minute flaws and patches, to large 
masses of dry sand, which more than once occurred during the pro- 
gress of our excavations in the heart of otherwise hard, sound rock.” 
He says that these beds of dry sand lay just above the level of 
high water, and were “ covered by cliffs of good rock sometimes 
Geological Society Transactions for 1837, vol. v. 
