ring the level of the sea at the time of their observations with
that indicated by the ancient marks, they found that the Baltic was
lower relatively to the land in certain places, but the amount of change
during equal periods of time had not been everywhere the same. During
their survey, they cut new marks for the guidance of future observers,
several of which I had an opportunity of examining fourteen years after
(in the summer of 1834), and in that interval the land appeared to me to
have risen at certain places north of Stockholm four or five inches. I
also convinced myself, during my visit to Sweden, after conversing with
many civil engineers, pilots, and fishermen, and after examining some
of the ancient marks, that the evidence formerly adduced in favor of the
change of level, both on the coasts of Sweden and Finland, was full and
satisfactory.[734] The alteration of level evidently diminishes as we
proceed from the northern parts of the Gulf of Bothnia towards the
south, being very slight around Stockholm. Some writers have indeed
represented the rate of depression of the waters at Stockholm as very
considerable, because certain houses in that city which are built on
piles have sunk down within the memory of persons still living, so as to
be out of the perpendicular; and this in consequence of the tops of the
piles giving way and decaying, owing to a fall of the waters which has
exposed them to be alternately wet and dry. The houses alluded to are
situated on the borders of Lake Maeler, a large lake, the outlet of
which joins the Baltic, in the middle of Stockholm. This lake is
certainly lower than formerly; but the principal cause of the change is
not the elevation of the land, but the removal of two old bridges built
on piles, which formerly obstructed the discharge of the fresh water
into the sea. Another cause is the opening, in the year 1819, of a new
canal at Sodertelje, a place south of Stockholm, by means of which a new
line of communication was formed between Lake Maeler and the
Baltic.[735]

It will naturally be asked, whether the mean level of a sea like the
Baltic can ever be determined so exactly as to permit us to appreciate a
variation of level, amounting only to one or two feet. In reply, I may
observe, that, except near the Cattegat, there are no tides in the
Baltic; and it is only when particular winds have prevailed for several
days in succession, or at certain seasons when there has been an
u