Of the Bogs in Ireland. 367 



ing in the degree of blackness and compactness propor- 

 tionate to its depth : near the bottom of the bog it forms a 

 black mass, which when dry has a strong resemblance to 

 pitch or bituminous coal, and having a conchoidal fracture 

 10 every direction, with a black shining lustre, and sus- 

 ceptible of receiving a considerable polish. 



" W« have requested Mr. Griffith to make a chemical 

 analysis of these different strata, which he has done in the 

 laboraury of the Dublin Society, and an account of which, 

 with the section above alluded to, forms the Appendix to 

 his Report. Immediately below this lower stratum, there is 

 generally found a thin stratum of yellow or blue clay, va- 

 rying in thickness from one to six feet ; in some places the 

 peat rests on a thinner stratum of yellowish white marl, 

 containing on an average about 60 per cent, of calcareous 

 matter ; this stratum of clay in this district universally rests 

 on a solid mass of clay and limestone gravel mixed together, 

 and extending to an unknown depth. 



" We should further consider the peat moss as partaking 

 in its general nature of the property of sponge completely 

 saturated with water, and giving rise to different streams 

 and rivers for the discharge of the surplus waters which it 

 receives from rain or snow : these streams in this district 

 almost universally have worn their channels through the 

 substance of the bog down to the clay or limestone gravel 

 underneath, dividing the bog into distinct masses, and pre- 

 senting in themselves the most proper situations for the 

 main drains, and which, with the assistance of art, may be 

 rendered effectual for that purpose. 



" Such is the internal structure of the bogs in this 

 district. 



" Viewing them externally, they present surfaces by no 

 means level, but with planes of inclination amply sufficient 

 for their drainage : the highest summit of any part of the 

 bogs in this district, is 298 feet above the level of the sea, 

 taken at an ordinary spring-tide in the Bay of Dublin ; 

 while the lowest point any where on their surface is 84 

 feet lower than the highest, and therefore 214 feet above 

 the level of the sea. 



" It requires a mere inspection of the map and sections, 

 to be convinced that there is no part of these bogs from 

 which the water may not be discharged into rivers in their 

 immediate vicinity, and with falls adequate to their drain- 

 age ; and we observe, that in the instance of the liog of 

 Timahoe, a part of its water is discharged into the sea at 

 Drogheda, and another part below Waterford/' 



The 



