424 Proceedings of the Royal Society 
able, — whilst the heat of the climate is great ; and there are fre- 
quently strong parching winds, which promote evaporation. 
The different forms of the stalactite deposits are believed to 
be formed in the following manner : — When the water, after per- 
colating the limestone rock, reaches the roof of the cave, and in 
such quantity as to drop copiously and rapidly, the evaporation 
takes place, both during the falling of the water to the floor of the 
cave and after it reaches the floor. In that case the calcareous 
matter accumulates on the floor, and if the water continues to drop 
long enough from the same part of the roof, the deposit gradually 
rises up in a columnar form. These are the Stalagmites. 
If, however, the water is less abundant, and the drops less fre- 
quent, evaporation takes place whilst they are adhering to the 
roof. In that case the drops of water thicken on the roof itself 
into a calcareous paste, and icicle-looking deposits are formed. 
These are the Stalactites. 
The two forms of deposit were indicated on a sketch exhibited, 
and were illustrated by specimens on the table, which Professor 
Allman had allowed to be brought over from the College Museum. 
Much larger specimens, however, of both kinds, had been brought 
to the Museum, — one of these, a stalagmite, about 6 feet high, 
now at the door of the Museum. Another, to be more particularly 
described, was too ponderous to be placed there ; it had always lain 
in the vestibule of the Mathematical Class-Eoom. 
Its length is, II feet 3 inches. 
„ average diameter at the base, . 2 ,, 1 „ 
„ girth half-way between base and top, 7 ,, 4 „ 
Supposing that there are 44 cubic feet of stone in this stalagmite, 
and that each cubic foot weighs 170 lbs., the weight would be 
nearly tons. 
The cave from which this stalagmite was taken is situated at 
Walsingham, in the parish of Hamilton, and upon the side of a hill, 
about 40 or 50 feet above the sea, and a quarter of a mile distant from 
it. The author remembered the cave well, having, with his brother, 
been in Bermuda with Sir David Milne during his command. 
The cave inside might be about 25 or 30 feet high at the greatest 
height of the roof, about 50 or 60 yards in length, and 20 to 30 
yards in breadth. But it is quite irregular in shape. It contains 
