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by the sun at the brink of ri-
vers, it is because the bottom, be-
ing an opaque body, is heated by
the rays which the water transmits.
Now, every heated body commu-
nicates that heat to all adjoining
bodies ; the water accordingly de-
rives heat from the bottom. If the
water be very deep, so that the rays
cannot penetrate to the bottom, it
has no preceptible heat, though the
sun bears upon it.
As air is a very transparent body,
to a much higher degree than ghass
or water, it follows, that it cannot
be heated by the sun, because the

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immediately produce any effect

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remote from terrestrial bodies, to receive a communication of heat from them; they act only upon Much as are adjacent. Hence you will easily perceive, that the rays of the sun cannot produce any effe&t in regions of the air very much elevated above the surface of the earth; and that the same degree of cold must always, and universally, prevail in such regions, as the full has no influence there, and as the heat of terrestrial bodies cannot be communicated so far. This is nearly the case on the summit of very high mountains, where it is always much colder than on plains and in vallies *. The city of Quito, in Peru, is almost under the equator, and were we to form our judgment from its fituation on the globe, we would suppose it oppressed with intolerable heat; the air, however, is a

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The heat of the solar rays, intercepted by the cloud, can produce no change in the inferior temperature, as it would

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- - Account

The heat that is felt when such

have been transmitted from the

C c 4 &nd

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found a large uncommon bird fluttering in the heath, but not wounded, which he brought home alive. On examination it proved to be Colymbus glacialis, Linn : the great speckled diver or loon, which is most excellently described in Willoughby's ornithology. Every part and proportion of this bird is so incomparably adapted to its mode of life, that in no instance do we see the wisdom of God in the creation to more advantage. The head is sharp, and smaller than the part of the neck adjoining, in order that it may pierce the water; the wings are placed forward and out of the center of gravity, for a purpose which shall be noticed hereafter; the thighs

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give strength and increase the power of swimming. The foot, when expanded, is not at right angles to the leg or body of the bird: but the exterior part inclining towards the head forms an acute angle with the body ; the intention being not to give motion in the line of the legs themselves, but by the combined impulse of both in an intermediate line, the line of the body. Most people know, that have observed at all, that the swimming of birds is nothing more than a walking in the water, where one foot succeeds the other as on the land; yet no one, as far as I am aware, has remarked that diving fowls, while under water, impel and row themselves forward by a motion of their wings, as well as . by the impulse of their feet: but such is really the case, as any person may easily be convinced who will observe ducks when hunted by dogs in a clear pond. Nor do I know that any one has given a reason why the wings of diving fowls are placed so forward: doubtless, not for the purpose of promoting their speed in flying, fince that position certainly impedes it;

The following table exhibits the average heat of places on the level of the sea, computed by the celebrated astronomer, professor Meyer, for every five degrees of

latitude.

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By comparing this table with the preceding, it

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titude, the altitude of the curve of congelation, or where the average temperature

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but

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