122 Rev. W. Smith on Deposits of Diatomaceous Earth 
that town, and about fifteen from Belfast. It occupies a basin 
in a plateau which does not appear to have any land of a much 
greater elevation in the immediate neighbourhood ; the lake is 
therefore fed by the surface-drainage of a very small district, and 
has no further apparent sources of supply, with the exception of 
a spring at the north-west corner, the produce of which is of 
little importance. It is however worthy of note, that a small 
stream, sufficient to turn the wheel of a corn-mill in the neigh- 
bourhood, approaches within a few hundred yards of the lake, 
and falling into a natural pit or cavity, is lost to view, and is said 
to reappear at some distance southwards, and there unite its 
waters with those of the streamlet flowing from the lake, to 
whose larger mass it had thus fastidiously refused to contribute 
its supply. However this may be, it is certain that the lake 
itself is not subject to any serious disturbance from the sudden 
increase of its waters by floods or otherwise, and that its quiet 
depths and great purity are peculiarly favourable to the develop- 
ment of Diatomacee. The level of the water however appears to 
have been lowered to the extent of several feet by deepening the 
outlet from the lake, a course which seems to have been adopted 
in the hope of increasing the supply to a mill now in ruins, a 
fate not unnaturally the result of so reckless an expenditure of 
the capital represented by the waters of the natural reservoir, 
thus improvidently drained of its contents. The facts I have 
mentioned will account for the circumstances to which I proceed 
more particularly to refer, and which I noted during a brief sur- 
vey of the shores of the lake in company with Mr. Geo. C. Hynd- 
man and Mr. J. G. Smith on the 6th Sept. 1849. 
On the north-east shore of the lake, at the height of about 
four or five feet from the present level of its waters, there occurred 
a stratum of diatomaceous earth corresponding with that alluded 
to in the opening of this paper. This layer was about six inches 
in depth and of great purity, containing but little foreign matter, 
and that chiefly the decayed filaments of the water-plants to which 
the living Diatomacee had been attached, or in company with 
which they had floated to their present position. This deposit 
when moist was of a dull gray colour, and resembled soft, freshly 
made soap; when placed upon the tongue, the taste was that of 
a smooth oleaginous substance. The sensation thus perceived is 
no doubt to be attributed to the extreme minuteness of the shells 
and their usually rounded outline, presenting no angles to grate 
upon the papille of the tongue or finger. When dried in mass, 
the earth is of a delicate cream-colour, when pulverized of a pure 
white, and forms, as I have proved, an excellent material for 
polishing silver plate. This layer must have required a long 
series of years for its gradual accumulation: its elevation from 
