252 Account of the Bursting of a Bog in Ireland, 



the observations and enquiries I made on the spot : preliminary 

 to which, a brief outline of the nature, extent, supposed origin 

 of, and organic and inorganic objects preserved in, bogs, may 

 not, perhaps, be altogether out of place. 



A variety of plants go to make peat : no less than forty 

 different species are enumerated by Dr. Macculloch {Western 

 Islands) ; and, of these, as many as seventeen are, according 

 to Dr. Rennie (Essays on Peat), mosses; the chief of which, 

 the Sphagnum palustre, possesses the remarkable property 

 of throwing up shoots in its upper part, while its lower extre- 

 mities are decaying : this moss, indeed, may be pronounced to 

 be the chief constituent of peat. \_Fig. 34<., S. obtusifolium 

 Ehr.;Jig. 35., squarrosum Web.; Jig. 36. acutifolium Ehr. ; 

 Jig. 37., cuspidatum Ehrh.*'] Rushes and reeds, however, of 



s * 3s 36 ihj niiLr 



14650 14651 X^r 14652^ ^^ 14653 



different species, are perfectly recognisable in many bogs, be- 

 sides a great variety of other plants, as already stated. 



As to the composition of peat, as shown to us by analysis, Sir 

 Humphry Davy informs us that, " in general, one hundred 

 parts of dry peat contain from sixty to ninety-nine parts of 

 matter destructible by fire ; and the residuum consists of 



[* The following information on sphagnum s (Sphagna) is from John- 

 ston's Flora of Berwick on Tweed, vol. ii. p. 55. " The Sphagna grow in 

 compact elastic knolls, and, by their decomposition, contribute greatly to 

 the formation of peat. Their stems are about a span [7 in.] in length, 

 branched, and densely clothed with soft nerveless beautifully reticulated 

 leaves, of a straw-yellow colour, and which distinguish the genus from 

 almost all other mosses. The Laplanders, Icelanders, and the North 

 American Indians use the Sphagna for lining their neat and curious 

 cradles. The moss forms a soft elastic bed, which absorbs moisture very 

 readily, and affords such a protection from the cold of a rigorous winter, 

 that its place would be ill supplied by cloth. Mr. W. Curtis obtained the 

 reward of the Society of Arts for his valuable application of these mosses 

 to the packing of young trees for exportation." This information is in- 

 teresting separately, and includes some matter correlative with Mr. Hunter's 

 subject] 



