CATARACTS, AND INUNDATIONS. 22? 



called a quaking bog, and as it rises and becomes drier, and the 

 grass roots and other vegetables become more putrid, together with 

 the mud and slime of the water, it acquires a blackness, and becomes 

 what is called a turf bog. I believe when the vegetables rot, the 

 saline particles are generally carried away with the water, in which they 

 are dissolved ; but the oily or sulphureous remain and float on the 

 water; and this is that which gives turf its inflammability. To make 

 this appear, it is to be observed, that in Ireland the highest moun- 

 tains are covered with bogs as well as the plains, because the 

 mountains abound much in springs. Now these being uninhabited, 

 and no care being taken to clear the springs, whole mountains are 

 thus over-run with bogs. 



It is to be observed also, that Ireland abounds in moss more than 

 probably any other country, insomuch that it is very apt to spoil 

 fruit-trees and quicksets. This moss is of divers kinds, and that 

 which grows in bogs is remarkable ; for the light spongy turf is 

 nothing but a congeries of the threads of this moss, before it be 

 sufficiently rotten ; and then the turf looks white, and is light. It 

 is seen in such quantities and is so tough, that the turf-spades can- 

 not cut it. In the north of Ireland they call it old-wives tow, as it 

 is not much unlike flax ; the turf-holes in time grow up with u u#ain 5 

 as well as all the little gutters in the bogs; and to it the red or lurf- 

 bog is probably owing; and from it even the hardened turf, when 

 broken, is stringy, though there plainly appear in it parts of other 

 vegetables ; and it is probable that the seed of this bog moss, 

 when it falls on dry and parched ground, produces heath. 



It is further to be observed, that the bottom of bogs is generally 

 a kind of white clay, or rather sandy marl; that a little water 

 makes it exceedingly soft ; and when dry, it is all dust ; so that the 

 roots of the grass do not stick fast in it ; but a little wet loosens 

 them, and the water easily gets in between the surface of the earth 

 and them, and lifts up the surface, as a dropsy doth the skin. 

 Again, bogs are generally higher than the land about them, and 

 highest in the middle ; the chief springs that cause them being com- 

 monly about the middle, from whence they dilate themselves by 

 degrees ; and besides if a deep trench be cut through a bog, you 

 will find the original spring, and vast quantities of water will be 

 discharge- 1, and the bog subside. 



It must be allowed that there arc quaking bogs otherwise prp. 



8* 



