village and Olburg, the Poter, Pellenberg, and the Camillenberg, which
last rises about one thousand feet above the level of the surrounding
surface. There are many others extending for some distance in the Eiffel
chain and in the vicinity, but those I have mentioned are sufficient to
guide the footsteps of the inquirer. The basin of the Lake of Laach is
nearly circular and crateriform; it is a mile and a half long, and about
a mile and a quarter in breadth. Its average depth is two hundred feet,
but it is full of holes, the measure of which is very uncertain. Its
water is blueish, very cold, and of a nasty brackish taste. It has been
examined by several geologists, British and foreign, among whom is the
famous Humboldt, and there is no doubt that this great reservoir is the
crater of an extinct volcano. The fragments and minerals thrown up on
the banks are analogous to those found in other volcanic countries; and
on one side (that towards Nieder-mennig) is a regular rock of continued
lava, which is supposed to have flowed from the crater during the last
eruption. Mr. Scrope, whose opinion is entitled to great weight, thinks
it not improbable that this may have been the eruption recorded by
Tacitus, (13 lib. Annal.,) as having ravaged the country of the
Initones, near Cologne, in the reign of Nero. I should not forget to
mention that there is a cavern within the basin of the lake, the air of
which is so stifling and noxious, that animals die if forced to remain
in it, and lights are extinguished by the gas--phenomena precisely
similar to those of the well-known Grotto del Cane, near Naples.

While I am on the subject of volcanic phenomena, I may as well add a
word on the origin of the trass or tufa, which is so thickly spread over
this country. It is similar to that found near Naples, at Mont d'Or,
Carbal, and other parts of Italy; and, indeed, all the products of the
latter district are pretty nearly the same as these, allowing for the
difference of a slate surface in the one case, and a sandy and alluvial