CHAP. XII.
In what way Verticity exists in any Iron that has
been smelted though not excited by a lodestone.
aving thus far211 demonstrated natural and inborn causes and powers acquired by means of the stone, we will now
examine the causes of magnetick virtues in smelted iron that has not been excited by a stone. Loadstone and iron furnish
and exhibit to us wonderful subtilities. It has been repeatedly shown above that iron not excited by a stone turns north
and south; further that it has verticity, that is, special and peculiar polar distinctions, just as a loadstone, or iron
which has been rubbed upon a loadstone. This indeed seemed to us at first wonderful and incredible; the metal of iron
from the mine is smelted in the furnace; it runs out of the furnace, and hardens into a great mass; this mass is divided
in great worksteads, and is drawn into iron bars, from which smiths again construct many instruments and necessary pieces
of iron-work. Thus the same mass is variously worked up and transformed into very many similitudes. What is it, then,
which preserves its verticity, and whence is it derived? So take this first from the
above212 smithy. Let the blacksmith beat out upon his anvil a glowing mass of
iron of two or three ounces weight into an iron spike of the length of a span of nine inches. Let the smith be standing
with his face to the north, his back to the south, so that * the hot iron on being struck has a motion of
extension to the north; and let him so complete his work with one or two heatings of the iron (if that be required); let
him always, however, whilst he is striking the iron, direct and beat out the same point of it toward the north, and let
him lay down that end toward the north. Let him in this way complete two, three, or more pieces of iron, nay, a hundred
or four hundred; it is demonstrable that all those which are thus beaten out toward the north, and so placed whilst they
are cooling, turn round on their centres; and floating pieces of iron (being transfixed, of course, through suitable
corks) make a motion in the water, the determined end being toward the north. In the same way also pieces of iron acquire
verticity from their direction whilst they are being beaten out and hammered or drawn out, * as iron wires are accustomed to do toward some
point of the horizon between east and south or between south and west, or in the opposite direction. Those, however,
which are pointed or drawn out rather toward the eastern or western point, conceive * hardly any verticity or a very undecided one.
That verticity is especially acquired by being beaten out. But a somewhat inferior iron ore, in which no magnetick powers
are apparent, if put in a * fire (its
position being observed to be toward the poles of the world or of the earth) and heated for eight or ten hours, then
cooled away from the fire, in the same position towards the poles, acquires a verticity in accordance with the position
of its heating and cooling. Let a rod of cast iron be heated red-hot in a strong fire, in which it lies * meridionally (that is, along the path of a
meridian circle), and let be removed from the fire and cooled, and let it return to its former temperature, remaining in
the same position as before; then from this it will turn out that, if the same ends have been turned to the same poles of
the earth, it will acquire verticity, and the end which looked toward the North on water with a cork before the heating,
if it have been placed during the heating and cooling toward the fourth, now turns round to the south. But if perchance
sometimes the rotation have been doubtful and somewhat feeble, let it be placed again in the fire, and when it is taken
out at a red heat, let it be perfectly cooled toward the pole from which we desire the verticity, and the verticity will
be acquired. Let the same rod be heated * in the contrary position, and let it be placed so
at a red heat it is cool; for it is from its position in cooling (by the operation of the verticity of the earth) that
verticity is put into the iron, and it turns round to parts contrary to its former verticity. So the end which formerly looked toward the north now turns to the south. In accordance with these
reasonings and in these ways the boreal pole of the earth gives to the end of a piece of iron turned toward it a southern
verticity, and that end is attracted by that pole. * And here it must be observed that this happens to
iron not only when it is cooled in the plane of the horizon, but also at any angle to it almost up to the perpendicular
toward the centre of the earth. So the heated iron conceives vigour and verticity from the earth more quickly in the
course of its return to its normal state, and in its recovery, as it were (in the course of which it is transformed),
than by its mere position alone. This is effected better and more * perfectly in winter and in colder air, when the
metal returns more certainly to its natural temperature, than in summer and in warm regions. Let us see also what
position alone and a direction toward the poles of the earth can effect by itself without fire and heat. Iron rods which
have been placed and fixed for a long time, twenty * or more years, from south to north (as they not
infrequently are fixed in buildings and across windows), those rods, I say, by that long lapse of time acquire verticity
and turn round, whether hanging in the air, or floating (being placed on cork), to the pole toward which they were
pointing, and magnetically attract and repel a balanced iron magnetick; for the long continued position of the body
toward the poles is of much avail. This fact (although conspicuous by manifest experiments) is confirmed by an incident
related in an Italian letter213 at the end of a book of Maestro Filippo Costa,
of Mantua, Sopra le Compositioni degli Antidoti written in Italian, which translated runs thus: "A druggist of
Mantua showed me a piece of iron entirely changed into a magnet, drawing another piece of iron in such a way that it
could be compared with a loadstone. Now this piece of iron, when it had for a long time held up a brick ornament on the
top of the tower of the church of St. Augustine at Rimini, had been at length bent by the force of the winds, and
remained so for a period of ten years. When the monks wished to bend it back to its former shape, and had handed it over
to a blacksmith, a surgeon named Maestro Giulio Caesare discovered that it was like a magnet and attracted iron." This
was caused by the turning of its extremities toward the poles for so long a time. And so what has been laid down before
about change of verticity should be borne in mind; how in fact the poles of iron spikes are altered, when a loadstone is
placed against them only with its pole and points toward them, even at a rather long distance. Clearly it is in the same
way that that large magnet also (to wit, the earth itself) affects a piece of iron and changes its verticity. For,
although the iron may not touch the pole of the earth, nor any magnetick part of the earth, yet verticity is acquired and
changed; not because the poles of the earth and the point itself which is 39° distant from our
city of London, changes the verticity at a distance of so many miles; but because the whole magnetick earth, that which
projects to a considerable height, and to which the iron is near, and that which is situated between us and the pole, and
the vigour existing within the orbe of its magnetick virtue (the nature of the whole conspiring thereto), produces the
verticity. For the magnetick effluence of the earth rules everywhere within the orbe of its virtue, and transforms
bodies; but those things which are more similar to it, and specially connected with it by nature, it rules and controls;
as loadstone and iron. Wherefore in very many matters of business and actions it is clearly not superstitious and idle to
observe the positions and conditions of lands, the points of the horizon and the places of the stars. For as when a babe
is brought forth into the light from its mother's womb, and acquires respiration and certain animal activities, then the
planets and celestial bodies214, according to their position in the universe,
and according to that configuration which they have with regard to the horizon and the earth, instil peculiar and
individual qualities into the newly born; so that piece of iron, whilst it is being formed and lengthened out, is
affected by the common cause (to wit, the earth); whilst it is returning also from its heated condition to its former
temperature, it is imbued with a special verticity in accord with its position. Rather long pieces of iron sometimes have
the same verticity * at each end;
wherefore they have motions which are less certain and well ordered on account of their length and of the aforesaid
processes, exactly as when an iron wire four feet long is rubbed at each end upon the same pole of a loadstone.