502 Scientific Proceedings, Royal Dublin Socieiy. 
bogs in the district of the Inny and Lough Ree that “some drains — 
6 to 7 feet wide, and as many deep, had been made from the — 
centre of the bog to its outlet: these were about 20 perches 
asunder, and although they had been finished for twenty years, 
and were not choked up, the bog did not appear to have been 
affected by them.’ 
The Commissioners remark on this subject that the lakes on 
bogs are situated in hollows, and the material forming the banks 
of these is more solid than that of the general crust.* 
We see no reason to doubt the correctness of the accepted view, — 
which regards a peat bog as consisting of a fluid interior, more 
or less viscous, and an outer felted crust. The closing up of drains 
and canals, cut into hogs, is a familiar phenomenon which supports 
this view. It has been remarked by Sir R. Griffith, who states 
that “every kind of bog drain will in time become narrower at 
the top than when originally formed; the drains made by the 
canal company. . . have now become considerably narrower at 
the top”’;? and by Mr. G. H. Kinahan, who informs us that on 
one occasion he opened a canal in the hard margin of a bog, 20 feet 
deep and 380 feet wide at the top; this, twelve years later, was — 
reduced to a depth of from 5 to 6 feet, and to about the same width. — 
Mr. Kinahan predicts that in ten or fifteen years’ time the site of — 
the recent debacle will be scarcely visible; the present depres- — 
sion in the bog will have become converted into a hollow from 
10 to 15 feet below the level of the surrounding bog. 
Although the felted envelope of a bog is close enough at its 
margins to afford support to the fluid interior, it is often broken by — 
holes in the middle; into these the soft, black fluid of the interior — 
oozes up, as everyone who has traversed a wet bog is well aware. 
Through such openings rain-water may make its way, and join 
the liquid accumulation below the crust. 
All mountain bogs present very similar features; and the fact - 
which appears most wonderful is not that they burst, but that they 
do not do so more frequently. 
Evidently the crust, in its natural state, is, as a rule, equal to 
1 Second Report, Commission on Bogs, p. 6, 1811. 2 Tbid., p. 6. 
3 Tbid., p. 9. 
