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page xxxix:-
conceive why, in a day when hardly a single breeze is
a-stir, the surface of a lake, which is as smooth as a
mirror, should, without any apparent cause, begin to be in
motion, which in less than an hour rises to a considerable
swell, with a direction sometimes to one quarter and
sometimes to another; yet such is really the case, and
similar appearances have been observed in some of the Alpine
lakes, though it has been imputed as a lie to Buchannan,
that he tells of a similar phaenomenon being frequent in the
lake of Lenox. I have formed a theory to account for it, but
as I have not had the opportunity of making a sufficient
number of observation, shall omit it here.
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The Bosom-Wind is quite a different affair, and takes place
wherever one object in the direction of the wind overlooks
another, or universally where any thing breaks the current
of the air that would otherwise impinge directly on the
objects beyond it; this is particularly the case where large
rocks screen things below them from the direct force of the
wind, yet subject them to what is called a Bosom-Wind. Near
the sources of the Caldew is a valley called Swineside,
never visited by the rays of the sun during the Winter
months: on the northern side of the hill which overshadows
it in this manner, and at a considerable height above the
valley, is a pretty large bason of water, called
Booth-scale-tarn; three fourths of which is surrounded
either by an exceedingly steep heath, or by entire rocks,
and the fourth, being the side right above the valley, gives
an outlet to the water. A road leads from the low grounds to
this lake, and from the outlet winds above half round it,
gradually ascending to some rocks where are slate-quarries,
on account of which it was first made; near these quarries
the road is a considerable height above the lake, and the
perpendicular height of the hill above it cannot be less
than four hundred yards; on the other side of this height
the descent is at an angle of perhaps fifty degrees, but on
this at a much greater. On a wet and windy day, in Autumn, I
once took a ride with two companions to this lake: the wind
blew directly over the height which I mentioned, not
striking upon us except in uncertain puffs, on account of
the intervention of the hill; that is, the wind, inpinging
on the inclined plane of the other side of the hill, was
compelled, towards the summit of it, in an oblique
direction, its powers continually increasing, and itself
being more and more condensed by the addition of fresh air
pressing on its course in a similar diverted manner. This
current at the summit met with the regular wind, and after
striking violently on the mass of air moving in higher
regions, was, by means of a combination of the weight and
motion of that air, at last repelled into the tranquil and
stagnant air beneath, where there was not a resistance from
motion, and thus occasioned the wind of which I am speaking.
It was this wind which amused me very much at that time: I
was looking at the lake beneath, and saw it grow black near
the centre; the spot where this first appeared changed
directly into a livid appearance, by being contrasted with
the rest of the water, through which from this spot, as a
fixed point, rolled concentric circles of waves towards the
circumference in a tumultuous manner, whilst the centre
itself remained quite smooth and undisturbed. The wind which
produced this agitation immediately after ascended the sides
of the bason, and affected us with very great force; I could
also observe the heath on the other sides of the pool shook
by the same, and in the same main direction from a centre
very forcibly. Such was the effects that I observed: I am
told, however, that others have known a wind of the same
kind, in dry weather, snatch the water out of the pool, and
scatter it as spray through the whole of this imprisoned
space.
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As I am now to speak of the Helm-Wind, it may be necessary,
for the sake of those readers who have not seen any thing of
the kind, to premise, that Cross-fell is one-continued
ridge, stretching without any branches, or even subject to
mountains, except two or three conical hills called Pikes,
from the N.N.W. to the S.S.E. from the neighbourhood of
Gillsland almost to Kirkby-Steven, that is above 40 miles.
Its direction is nearly in a right line, and the height of
its different parts not very unequal; but is in general
such, that some of its more eminent parts are exceeded in
altitude by few hills in Britain, and perhaps not by any in
England. As it rises in the interior part of the country, it
has in some degree an effect on the weather on its different
sides,
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