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Things to Be Considered, Or Written Fully About
(First Series)
by Jonathan Edwards
1. To observe, that
Incurvation, Refraction, and Reflexion, from concave surfaces of drops
of water, etc., is from Gravity.
2. To observe, that it is likely, that the Attraction of particles of
Heat contributes as much towards the burning of bodies, as the Impulse.
3. To observe, that water may quench fire, by insinuating itself into
the pores, and hindering the free play of the particles, and, by reason
of its softness and pliableness, deadening that motion, like throwing a
stone upon a feather-bed.
4. To observe, that, if we do suppose an infinite number of Surfaces in
the Universe, yet, according to the number, so must be the smallness.
5. To observe, that the cause that an object appears not double, being
seen with two eyes, is, that all the parts upon the retina, that exactly
correspond, end upon the same spot of the surface in the brain, which
receives the images.
6. To observe, that one end of Respiration is, that the motion in the
chest may be communicated to the other parts of the body.
9. To show, that the different refrangibility of rays must of necessity
be owing, either to their different velocity, or different magnitude;
because, there can be no other reason, of their different attractability,
which, indeed, is refrangibility.
11. To show, from (Sir) Isaac Newton’s principles of light and colours,
why the sky is blue; why the Sun is not perfectly white, as it would be,
if there were no atmosphere, but somewhat inclining to a yellow, even at
noon-day; why the Sun is yellow, when rising and setting, and sometimes,
in smoky weather, of a blood red; why the Clouds, and the Atmosphere,
near the horizon, appear red and yellow, before sun-rising, and after
sun-setting; why Distant Mountains are blue, etc.
13. To observe, that all the rays of one sort, being obstructed by any
medium, and others still proceeding, as by the air in smoky weather,
etc. — To enquire, how it can be; and to observe, that its so doing
makes it probable, that there are some other properties in light and
mediums, yet wholly unknown; and to observe, that the unaccountable
phenomena of reflexions prove the same thing; and to enquire, what it
is; and also, to seek out other strange phenomena, and compare them
altogether, and see what qualities can be made out of them: And if we
can discover them, it is probable we may be let into a New World of
Philosophy.
17. To observe, that the cause why Thunder, that is a great way off,
will sound very grum, which, near, is very sharp, as well as other
noises, instances of which are to be given, is, because the further
waves go, the wider they grow, and further asunder, as it is in water:
several of the little undulations, by travelling near together,
incorporate with the great one.
19. To observe, that the weight of the descending blood in the veins,
completely answers to the weight of the ascending blood in the arteries,
in parts above the heart; so that the weight of one, exactly balances
the weight of the other; and the descending blood in the veins pulls up
the blood in the arteries; and the weight of the blood in the arteries,
restrains the impetuosity of the descending blood in the veins; so that
the blood in both, ascending and descending, runs as easily and
uniformly, as if it ran all the while parallel to the horizon. So in the
parts below the heart, where the arterial blood descends, and the venal
ascends, barely the weight of the blood, in the arteries, is sufficient
to raise the blood in the veins even with it, as high as the beginning
of the arteries, according to the law of hydrostatics; and the weight of
the blood in the veins restrains that, which descends in the arteries,
so that the blood in these also moves, just as if it moved in a plain,
neither up nor down: and the heart has no more labour, to impel the
blood up the ascending trunk of the Aorta, nor ease in impelling it down
the descending trunk, than if it ran in a trunk parallel to the horizon.
Neither doth the blood ascend, with more difficult than it descends, but
with equal facility, both in arteries and veins, above and below the
heart; and to show the philosophy of this.
22. Relating to the 13th. To observe, that it is certain, that the
stopping of one sort of rays, and the proceeding of others, is not,
because that sort of rays alone are stopped, by striking against the
particles of the medium, from this experiment: viz. As I was under the
trees, I observed, that the light of the sun, upon the leaves of the
book I was reading, which crept through the crevices of the leaves of
the tree, was of a reddish purplish colour; which I supposed to be,
because many of the green rays were taken up, by the leaves of the tree,
and left all the rest tainted with the most opposite colour; which could
be no otherwise, than by stopping those green rays, which passed near to
the edges of the leaves.
— N. B.: that the light of
the sun, in this case, would not appear coloured, except the crevices,
through which the rays came, were very small.
Coroll. 1. Hence bodies do attract one sort of rays, more than another.
Coroll. 2. Hence it is certain, that bodies do attract the same sort of
rays most strongly, which they reflect most strongly.
Coroll. 3. Hence it is probable, that bodies do reflect, and attract, by
the same force; because that they both attract and reflect, the same
sort of rays.
27. It appears, that the visible particles of a morning Fog are not
single bubbles of water. I have seen a frozen fog, a fog of which these
particles were all frozen, as they floated in the air, which were all
little stars, of six points, like the particles of snow, very small, and
were not joined together, many of them into one flake, as in snow, but
floated single, and at a little distance looked every whit like other
fog, only not as thick as other fog often is, and not so thick as to
hinder the Sun from shining bright. It was evident that it was not a
fine snow; for it was otherwise a very clear morning, and there was not
a cloud any where to be seen above the horizon. It is therefore evident,
that, before they were frozen, they were not single bubbles; inasmuch as
a single bubble will not make one of those stars, no not less than
seven.
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