156 — On the Pitch Lake of Trinidad. 
These channels have heretofore been described as crevices or 
cracks in the pitch. This description is however incorrect for the 
material though apparently almost as pa as stone is yet far too 
plastic to admit of any thing like a fissure remaining open in it. 
Excavations from which many tons of pitch have been taken for 
exportation are closed up again in the course of a few days or. 
weeks, not by streams of pitch flowing into them but by the grad- 
ual closing i in of the sides ahd bottom 
annels are produced and maintained by the following 
singular process. Each of the many hundred areas into which the 
lake is divided ira an independent revolving motion in this 
wise. In the center of the area the pitch is constantly rising up 
—not Sanne: out in streams, but rising en masse. It is thus 
constantly displacing that which previously occupied the center 
and forcing it towards the circumference. 
The surface becomes covered with concentric wrinkles, and 
the interior structure somewhat laminated, while the upper lam- 
inze at the center of the area are torn into ee by the expan- 
sion like the outer bark of a rapidly growing tre 
Where the edge of such an expanding area sabete that of the ad- 
joining oné the pitch rolls under to be thrown up again in the 
center at some future period. The material is rarely soft enough 
ie meet and form a close joint at noe top but ee with a 
rounded edge and at a considerable a 
The spaces thus left between the different areas are often five 
or six feet deep and three or four yards re at the top, diminish- 
ing of course to a mere seam at the botto 
Where three or more of them meet a ec shaped cavity is 
formed in some cases twelve or fourteen feet dee 
It is difficult to conceive of a motion like this going on ina 
material sane of stony hardness, but that such a revolution is 
constantly ae place over the entire surface of this ake can- 
be dou 
Another curious proof of it is afforded by numerous pieces of 
wood which being involved in the pitch are constautly coming 
to the surface. ey are often several feet in length and five or 
six inches in diameter. On reaching the surface they generally 
asstime an upright position, one end being detained in the pitch 
while the other is elevated by the lifting of the middle. They 
may be seen at frequent intervals all over the lake standing up to 
the height of two or even three feet. They look like stumps of 
trees, protruding through the pitch, but their parvenu character is 
curiealy betrayed by a ragged cap of pitch which invariably 
covers the top and hangs down like hounds ears on either side. 
a Pega then to which a close observation leads us in 
regard to the present condition of this singular lake is, not that 
it has siddouly cooled down from a boiling state as heretofore de- 
fepihetes ak ar Soars 
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