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 Diatomacece. 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 Diatomacece 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 papillae of the tongue or finger. When dried in mass, 

 the earth is of a delicate cream-colour, when pulverized of a pui'e 

 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 



