: Report of Committee of Investigation on Bog-flow in Kerry. 499 
is evidently a function of the slope of the ground and the viscosity 
of the fluid, and the latter depends on the ratio between the 
amount of water and of solid contents present in the moving 
material. A difference also exists in the proportion of solid 
erust to liquid contents. The largest proportion of solid material 
is met with in the flow of 1745. In this case the bog shifted bodily, 
and the movement might, with more justice, than in most instances, 
be compared to that ofalandslip. The late eruption of Knockna- 
geeha was one of the largest on record, and is also characterised. 
by the unusually large proportion of water present in the liberated 
material. Hence its rapid flow. 
SuMMARY oF Previous EXPLANATIONS OF BoG-BURSTS. 
In giving the following short review, we desire to acknowledge 
our indebtedness to Klinge’s valuable paper alluded to below. 
Leonard’ remarks that “a great quantity of water collects in 
damp years on the bottom of the bog, which water held down by 
the turf seeks a subterranean outlet.” 
Bronn’ points out the living peat bog may absorb from 50 to- 
90 per cent. of water, and so swell to double its volume: it is to: 
this cause that the dome-like form is due. When the bog lies on 
an inclined plane, heavy rains will cause the bog to swell, and 
possibly burst. 
'  Lesquereux® states that if peat bogs are deep, and lie higher 
than the neighbouring country, and if the drainage is not properly 
attended to, water will accumulate at the bottom of the bog. As 
the surface does not rise any higher, and water is no longer 
absorbed by the vegetation, the lower layers of the peat become 
softened and converted into a kind of soup. ‘The crust of the bog 
bursts under the pressure of the contained fluid. 
Senfft* repeats Bronn’s view regarding excessive surface absorp- 
tion, adding that, if a bog swollen by rain is situated on a slope, it 
1 Mineralogische Taschenbuch ftir das Jahr 1823, 3 Abt., p. 861. 
2 Handbuch einer Geschichte der Natur. Bd. ii., Th. ii., Stuttgart, p. 496, 1843. 
3 Untersuchungen ueber Torfmoore, p. 165, 1847, Anmerk. 
B 4 Die Humus-, Marsch-, Torf-, und Limonitbildungen, p. 102, 1862. 
