The works of Francis Bacon, lord chancellor of England.

BooK II. NOVUM ORGANUM. 399
traction of the corporeal mass of the earth may nion are grounded chiefly upon this, that the moon
be taken as the cause of weight. reflects the sun's rays, and that light does not: Again, let the required nature be the polarity appear capable of being reflected, except by
of the steel needle, when touched with the solids. The instance of the crosswill, therefore,
magnet. We have these two ways with regard (if any,) be such as to exhibit reflection by a rare
to this nature. Either the touch of the magnet body, such as flame, if it be but sufficiently dense.
must communicate polarity to the steel towards Now, certainly one of the reasons of twilight is
the north and south, or else it may only excite the reflection* of the rays of the sun by the upper
and prepare it, whilst the actual motion is occa- part of the atmosphere. We see the sun's rays
sioned by the presence of the earth, which Gilbert also reflected on fine evenings, by streaks of
considers to be the case, and endeavours to prove moist clouds, with a splendour not less, but perwith so much labour. The particulars he has haps more bright and glorious, than that reflected
inquired into with such ingenious zeal amount to from the body of the moon, and yet, it is not
this: 1. An iron bolt placed for a long time to- clear that those clouds have formed into a dense
wards the north and south acquires polarity from body of water. We see also that the dark air,
this habit, without the touch of the magnet; as behind the windows at night, reflects the light
if the earth itself operating but weakly from its of a candle in the same manner as a dense body
distance, (for the surface or outer crust of the would do.t The experiment should also be made
earth does not, in his opinion, possess the mag- of causing the sun's rays to fall through a hole
netic power,) yet, bylong continued motion, could upon some dark and bluish flame. The unconsupply the place of the magnet, excite the iron, fined rays of the sun, when falling on faint flames,
and convert and change it when excited. 2. Iron, do certainly appear to deaden them, and render
at a red or white heat, when quenched in a direc- them more like white smoke than flames. These
tion parallel to the north and south, also acquires are the only instances which occur at present of
polarity without the touch of the magnet; as if the nature of those of the cross, and better, perthe parts of iron being put in motion by ignition, haps, can be found. But it must always be oband afterwards recovering themselves, were at served, that reflection is not to be expected from
the moment of being quenched more susceptible flame, unless it be of some depth, for otherwise
and sensitive of the power emanating from the it becomes nearly transparent. This at least may
earth, than at other times, and, therefore, as it be considered certain, that light is always either
were, excited. But these points, though well received and transmitted, or reflected by an even
observed, do not completely prove his assertion. surface.
An instance of the cross on this point might Again, let the required nature be the motion of
ne as follows. Let a small magnetic globe be projectiles (such as darts, arrows, and balls)
taken, and its poles marked, and placed towards through the air. The school, in its usual manner,
the east and west, not towards the north and treats this very carelessly, considering it enough
south, and let it continue thus. Then let an to distinguish it by the name of violent motion.,
untouched needle be placed over it, and suffered from that which they term natural, and as far as
to remain so for six or seven days. Now, the regards the first percussion or impulse, satisfies
needle, (for this is not disputed,) whilst it remains itself by its axiom, " that two bodies cannot
over the magnet, will leave the poles of the world, exist in one place, or there would be a penetration
and turn to those of the magnet, and, therefore, of dimensions." With regard to this nature we
as long as it remains in the above position will have these two crossways. The motion must
turn to the east and west. But if the needle, arise either from the air carrying the projected
when removed from the magnet, and placed upon body and collecting behind it, like a stream bea pivot, be found immediately to turn to the hind boats or the wind behind straws; or from
north and south, or even by degrees to turn the parts of the body itself not supporting the
thither, then the presence of the earth must be impression, but pushing themselves forward in
considered as the cause; but if it remains turned succession to ease it. Fracastorius, and nearly
as at first towards the east and west, or lose its all those who have entered into any refined inpolarity, then that cause must be suspected, and quiry upon the subject, adopt the first. Nor can
farther inquiry made. it be doubted, that the air has some effect, yet,
Again, let the required nature be the corporeal the other motion is, without doubt, real, as is clear
substance of the moon, whether it be rare, fiery, from a vast number of experiments. Amongst
and aerial, (as most of the ancient philosophers
have thought,) or solid and dense, (as Gilbert *Rather the refraction-the sky or air, however, reflects the
and many of the moderns, with some of the an- blue rays of light.
+ The polished surface of the glass causes the reflection in
cients, hold.)- The reasons for this latter opi- this case, and not the air; and a hat or other black surface
put behind the window in the day time will enable the glass
* A sufficient proof of its necessary solidity is now afforded to reflect distinctly for the same reason; namely, that tl.e
by the attraction of the sea, and the moon's motion around reflected rays are not mixed and confused with those trans
the earth. mitted from the other side of the window.