built, the floor of the cellar was constantly
under water, which is hardly likely to have been the case. He mentions
also the observations made at the sluices of the Maelar Lake, from
which a rise of one foot in a century had been inferred, but states
that a defect in the measuring-scale completely invalidates the
results. In addition to what the Academy are doing, he has had a
reference-mark cut on the face of the steep rock of the citadel, so
that, in the course of a few years, we shall be in a position to judge
in how far the theory of elevation and subsidence of land in Sweden is
borne out by the facts.

This reminds one that coral-reefs have been much talked about of late:
the opinion is, that they grow in height about an inch and a quarter
yearly. Means have also been taken to decide this question. When the
American Exploring Expedition lay at Tahiti, Captain Wilkes had a
stone-slab fixed on Point Venus, and the distance from it to the
Dolphin Shoal below carefully ascertained, so that future measurements
will test the theory.

Mr Wells, of Cambridge, Massachusetts, shews that there are causes,
besides those usually assigned, which will produce stratification, or
those interruptions which occur in deposits. He was engaged in
examination of soils; and washed earth through a filter, at times so
slowly as to occupy fourteen days in the process, and dried the
sediment at a temperature of 250 degrees. This, when dry, he found to
be perfectly stratified in divisional planes; sometimes accordant, at
others irregular, and shewing difference of material--namely, silica
and alumina:

'The strata so produced,' he says, 'were in some instances exceedingly
perfect and beautiful, not altogether horizontal, but slightly curved,
and in some degree conforming to the shape of the funnel. The
production of laminae was also noticed, especially by the cleavage of
the strata produced into thin, delicate, parallel plates, when
moistened with water. These arrangements, it is evident, were not
caused by any interruption or renewal of the matter deposited, or by
any change in the quality of the particles deposited, but from two
other causes entirely distinct, and which I conceive to be
these--first, from a tendency in earthy matter, subjected to the
filtering, soaking, and washing of water for a considerable period, to
arrange itself according to its degree of fineness, or, perhaps,
according to the specific gravity of the particles, a