On inspecting the planet Jupiter, a still more striking revelation was

made, as four tiny stars were observed to occupy an equatorial position

near that planet, and were seen, when watched night after night, to

be circling about the planet, precisely as the moon circles about

the earth. Here, obviously, was a miniature solar system--a tangible

object-lesson in the Copernican theory. In honor of the ruling

Florentine house of the period, Galileo named these moons of Jupiter,

Medicean stars.

Turning attention to the sun itself, Galileo observed on the surface

of that luminary a spot or blemish which gradually changed its shape,

suggesting that changes were taking place in the substance of the

sun--changes obviously incompatible with the perfect condition

demanded by the metaphysical theorists. But however disquieting for the

conservative, the sun's spots served a most useful purpose in enabling

Galileo to demonstrate that the sun itself revolves on its axis, since

a given spot was seen to pass across the disk and after disappearing

to reappear in due course. The period of rotation was found to be about

twenty-four days.

It must be added that various observers disputed priority of discovery

of the sun's spots with Galileo. Unquestionably a sun-spot had been

seen by earlier observers, and by them mistaken for the transit of an

inferior planet. Kepler himself had made this mistake. Before the day of

the telescope, he had viewed the image of the sun as thrown on a screen

in a camera-obscura, and had observed a spot on the disk which be

interpreted as representing the planet Mercury, but which, as is now

known, must have been a sun-spot, since the planetary disk is too

small to have been revealed by this method. Such observations as these,

however interesting, cannot be claimed as discoveries of the sun-spots.

It is probable, however, that several discoverers (notably Johann

Fabricius) made the telescopic observation of the spots, and recognized

them as having to do with the sun's surface, almost simultaneously with

Galileo. One of these claimants was a Jesuit named Scheiner, and the

jealousy of this man is said to have had a share in bringing about that

persecution to which we must now refer.

There is no more famous incident in the history of science than the

heresy trial through which Galileo was led to the nominal renunciation

of his cherished doctrines. There is scarcely another incident that has

been commented upon so variously. Each succeeding generation has put

its own interpretation on it. The facts, however, have been but little

questioned. It appears that in the year 1616 the church became at

last aroused to the implications of the heliocentric doctrine of the

universe. Apparently it seemed clear to the church authorities that the

authors of the Bible believed the world to be immovably fixed at the

centre of the universe. Such, indeed, would seem to be the natural

inference from various familiar phrases of the Hebrew text, and what

we now know of the status of Oriental science in antiquity gives full

warrant to this interpretation. There is no reason to suppose that the

conception of the subordinate place of the world in the solar system had

ever so much as occurred, even as a vague speculation, to the authors of

Genesis. In common with their contemporaries, they believed the earth to

be the all-important body in the universe, and the sun a luminary placed

in the sky for the sole purpose of giving light to the earth. There is

nothing strange, nothing anomalous, in this view; it merely reflects the

current notions of Oriental peoples in antiquity. What is strange and

anomalous is the fact that the Oriental dreamings thus expressed could

have been supposed to represent the acme of scientific knowledge. Yet

such a hold had these writings taken upon the Western world that not

even a Galileo dared contradict them openly; and when the church fathers

gravely declared the heliocentric theory necessarily false, because

contradictory to Scripture, there were probably few people in

Christendom whose mental attitude would permit them justly to appreciate

the humor of such a pronouncement. And, indeed, if here and there a man

might have risen to such an appreciation, there were abundant reasons

for the repression of the impulse, for there was nothing humorous about

the response with which the authorities of the time were wont to meet

the expression of iconoclastic opinions. The burning at the stake of

Giordano Bruno, in the year 1600, was, for example, an object-lesson

well calculated to restrain the enthusiasm of other similarly minded

teachers.

Doubtless it was such considerations that explained the relative silence

of the champions of the Copernican theory, accounting for the otherwise

inexplicable fact that about eighty years elapsed after the death of

Copernicus himself before a single text-book expounded his theory. The

text-book which then appeared, under date of 1622, was written by the

famous Kepler, who perhaps was shielded in a measure from the papal

consequences of such hardihood by the fact of residence in a Protestant

country. Not that the Protestants of the time favored the heliocentric

doctrine--we have already quoted Luther in an adverse sense--but of

course it was characteristic of the Reformation temper to oppose any

papal pronouncement, hence the ultramontane declaration of 1616 may

indirectly have aided the doctrine which it attacked, by making that

doctrine less obnoxious to Lutheran eyes. Be that as it may, the work of

Kepler brought its author into no direct conflict with the authorities.

But the result was quite different when, in 1632, Galileo at last broke

silence and gave the world, under cover of the form of dialogue, an

elaborate exposition of the Copernican theory. Galileo, it must be

explained, had previously been warned to keep silent on the subject,

hence his publication doubly offended the authorities. To be sure, he

could reply that his dialogue introduced a champion of the Ptolemaic

system to dispute with the upholder of the opposite view, and that, both

views being presented with full array of argument, the reader was left

to reach a verdict for himself, the author having nowhere pointedly

expressed an opinion. But such an argument, of course, was specious, for

no one who read the dialogue could be in doubt as to the opinion of the

author. Moreover, it was hinted that Simplicio, the character who upheld

the Ptolemaic doctrine and who was everywhere worsted in the argument,

was intended to represent the pope himself--a suggestion which probably

did no good to Galileo's cause.

The character of Galileo's artistic presentation may best be judged from

an example, illustrating the vigorous assault of Salviati, the

champion of the new theory, and the feeble retorts of his conservative

antagonist:

"Salviati. Let us then begin our discussion with the consideration that,

whatever motion may be attributed to the earth, yet we, as dwellers upon

it, and hence as participators in its motion, cannot possibly perceive

anything of it, presupposing that we are to consider only earthly

things. On the other hand, it is just as necessary that this same motion

belong apparently to all other bodies and visible objects, which, being

separated from the earth, do not take part in its motion. The correct

method to discover whether one can ascribe motion to the earth, and what

kind of motion, is, therefore, to investigate and observe whether in

bodies outside the earth a perceptible motion may be discovered which

belongs to all alike. Because a movement which is perceptible only in

the moon, for instance, and has nothing to do with Venus or Jupiter or

other stars, cannot possibly be peculiar to the earth, nor can its

seat be anywhere else than in the moon. Now there is one such universal

movement which controls all others--namely, that which the sun, moon,

the other planets, the fixed stars--in short, the whole universe, with

the single exception of the earth--appears to execute from east to west

in the space of twenty-four hours. This now, as it appears at the first

glance anyway, might just as well be a motion of the earth alone as of

all the rest of the universe with the exception of the earth, for the

same phenomena would result from either hypothesis. Beginning with the

most general, I will enumerate the reasons which seem to speak in favor

of the earth's motion. When we merely consider the immensity of the

starry sphere in comparison with the smallness of the terrestrial ball,

which is contained many million times in the former, and then think of

the rapidity of the motion which completes a whole rotation in one day

and night, I cannot persuade myself how any one can hold it to be more

reasonable and credible that it is the heavenly sphere which rotates,

while the earth stands still.

"Simplicio. I do not well understand how that powerful motion may be

said to as good as not exist for the sun, the moon, the other planets,

and the innumerable host of fixed stars. Do you call that nothing when

the sun goes from one meridian to another, rises up over this horizon

and sinks behind that one, brings now day, and now night; when the moon

goes through similar changes, and the other planets and fixed stars in

the same way?

"Salviati. All the changes you mention are such only in respect to

the earth. To convince yourself of it, only imagine the earth out of

existence. There would then be no rising and setting of the sun or of

the moon, no horizon, no meridian, no day, no night--in short, the said

motion causes no change of any sort in the relation of the sun to the

moon or to any of the other heavenly bodies, be they planets or fixed

stars. All changes are rather in respect to the earth; they may all be

reduced to the simple fact that the sun is first visible in China, then

in Persia, afterwards in Egypt, Greece, France, Spain, America, etc.,

and that the same thing happens with the moon and the other heavenly

bodies. Exactly the same thing happens and in exactly the same way if,

instead of disturbing so large a part of the universe, you let the earth

revolve about itself. The difficulty is, however, doubled, inasmuch as a

second very important problem presents itself. If, namely, that powerful

motion is ascribed to the heavens, it is absolutely necessary to regard

it as opposed to the individual motion of all the planets, every one of

which indubitably has its own very leisurely and moderate movement

from west to east. If, on the other hand, you let the earth move about

itself, this opposition of motion disappears.

"The improbability is tripled by the complete overthrow of that order

which rules all the heavenly bodies in which the revolving motion is

definitely established. The greater the sphere is in such a case, so

much longer is the time required for its revolution; the smaller the

sphere the shorter the time. Saturn, whose orbit surpasses those of all

the planets in size, traverses it in thirty years. Jupiter(4) completes

its smaller course in twelve years, Mars in two; the moon performs its

much smaller revolution within a month. Just as clearly in the Medicean

stars, we see that the one nearest Jupiter completes its revolution in

a very short time--about forty-two hours; the next in about three and

one-half days, the third in seven, and the most distant one in sixteen

days. This rule, which is followed throughout, will still remain if we

ascribe the twenty-four-hourly motion to a rotation of the earth. If,

however, the earth is left motionless, we must go first from the very

short rule of the moon to ever greater ones--to the two-yearly rule of

Mars, from that to the twelve-yearly one of Jupiter, from here to

the thirty-yearly one of Saturn, and then suddenly to an incomparably

greater sphere, to which also we must ascribe a complete rotation in

twenty-four hours. If, however, we assume a motion of the earth, the

rapidity of the periods is very well preserved; from the slowest sphere

of Saturn we come to the wholly motionless fixed stars. We also escape

thereby a fourth difficulty, which arises as soon as we assume that

there is motion in the sphere of the stars. I mean the great unevenness

in the movement of these very stars, some of which would have to revolve

with extraordinary rapidity in immense circles, while others moved very

slowly in small circles, since some of them are at a greater, others at

a less, distance from the pole. That is likewise an inconvenience,

for, on the one hand, we see all those stars, the motion of which is

indubitable, revolve in great circles, while, on the other hand, there

seems to be little object in placing bodies, which are to move in

circles, at an enormous distance from the centre and then let them

move in very small circles. And not only are the size of the different

circles and therewith the rapidity of the movement very different in the

different fixed stars, but the same stars also change their orbits and

their rapidity of motion. Therein consists the fifth inconvenience.

Those stars, namely, which were at the equator two thousand years ago,

and hence described great circles in their revolutions, must to-day

move more slowly and in smaller circles, because they are many degrees

removed from it. It will even happen, after not so very long a time,

that one of those which have hitherto been continually in motion will

finally coincide with the pole and stand still, but after a period of

repose will again begin to move. The other stars in the mean while,

which unquestionably move, all have, as was said, a great circle for an

orbit and keep this unchangeably.

"The improbability is further increased--this may be considered the

sixth inconvenience--by the fact that it is impossible to conceive what

degree of solidity those immense spheres must have, in the depths of

which so many stars are fixed so enduringly that they are kept revolving

evenly in spite of such difference of motion without changing their

respective positions. Or if, according to the much more probable theory,

the heavens are fluid, and every star describes an orbit of its own,

according to what law then, or for what reason, are their orbits

so arranged that, when looked at from the earth, they appear to be

contained in one single sphere? To attain this it seems to me much

easier and more convenient to make them motionless instead of moving,

just as the paving-stones on the market-place, for instance, remain in

order more easily than the swarms of children running about on them.

"Finally, the seventh difficulty: If we attribute the daily rotation to

the higher region of the heavens, we should have to endow it with force

and power sufficient to carry with it the innumerable host of the fixed

stars--every one a body of very great compass and much larger than the

earth--and all the planets, although the latter, like the earth, move

naturally in an opposite direction. In the midst of all this the little

earth, single and alone, would obstinately and wilfully withstand such

force--a supposition which, it appears to me, has much against it. I

could also not explain why the earth, a freely poised body, balancing

itself about its centre, and surrounded on all sides by a fluid medium,

should not be affected by the universal rotation. Such difficulties,

however, do not confront us if we attribute motion to the earth--such

a small, insignificant body in comparison with the whole universe, and

which for that very reason cannot exercise any power over the latter.

"Simplicio. You support your arguments throughout, it seems to me,

on the greater ease and simplicity with which the said effects are

produced. You mean that as a cause the motion of the earth alone is just

as satisfactory as the motion of all the rest of the universe with the

exception of the earth; you hold the actual event to be much easier

in the former case than in the latter. For the ruler of the universe,

however, whose might is infinite, it is no less easy to move the

universe than the earth or a straw balm. But if his power is infinite,

why should not a greater, rather than a very small, part of it be

revealed to me?

"Salviati. If I had said that the universe does not move on account of

the impotence of its ruler, I should have been wrong and your rebuke

would have been in order. I admit that it is just as easy for an

infinite power to move a hundred thousand as to move one. What I said,

however, does not refer to him who causes the motion, but to that

which is moved. In answer to your remark that it is more fitting for an

infinite power to reveal a large part of itself rather than a little, I

answer that, in relation to the infinite, one part is not greater than

another, if both are finite. Hence it is unallowable to say that a

hundred thousand is a larger part of an infinite number than two,

although the former is fifty thousand times greater than the latter. If,

therefore, we consider the moving bodies, we must unquestionably regard

the motion of the earth as a much simpler process than that of the

universe; if, furthermore, we direct our attention to so many other

simplifications which may be reached only by this theory, the daily

movement of the earth must appear much more probable than the motion

of the universe without the earth, for, according to Aristotle's just

axiom, 'Frustra fit per plura, quod potest fieri per p auciora' (It is

vain to expend many means where a few are sufficient)."(2)

The work was widely circulated, and it was received with an interest

which bespeaks a wide-spread undercurrent of belief in the Copernican

doctrine. Naturally enough, it attracted immediate attention from the

church authorities. Galileo was summoned to appear at Rome to defend his

conduct. The philosopher, who was now in his seventieth year, pleaded

age and infirmity. He had no desire for personal experience of the

tribunal of the Inquisition; but the mandate was repeated, and Galileo

went to Rome. There, as every one knows, he disavowed any intention to

oppose the teachings of Scripture, and formally renounced the heretical

doctrine of the earth's motion. According to a tale which so long passed

current that every historian must still repeat it though no one now

believes it authentic, Galileo qualified his renunciation by muttering

to himself, "E pur si muove" (It does move, none the less), as he rose

to his feet and retired from the presence of his persecutors. The tale

is one of those fictions which the dramatic sense of humanity is wont

to impose upon history, but, like most such fictions, it expresses the

spirit if not the letter of truth; for just as no one believes that

Galileo's lips uttered the phrase, so no one doubts that the rebellious

words were in his mind.

After his formal renunciation, Galileo was allowed to depart, but with

the injunction that he abstain in future from heretical teaching. The

remaining ten years of his life were devoted chiefly to mechanics, where

his experiments fortunately opposed the Aristotelian rather than the

Hebrew teachings. Galileo's death occurred in 1642, a hundred years

after the death of Copernicus. Kepler had died thirteen years before,

and there remained no astronomer in the field who is conspicuous in

the history of science as a champion of the Copernican doctrine. But in

truth it might be said that the theory no longer needed a champion. The

researches of Kepler and Galileo had produced a mass of evidence for the

Copernican theory which amounted to demonstration. A generation or two

might be required for this evidence to make itself everywhere known

among men of science, and of course the ecclesiastical authorities must

be expected to stand by their guns for a somewhat longer period. In

point of fact, the ecclesiastical ban was not technically removed by

the striking of the Copernican books from the list of the Index

Expurgatorius until the year 1822, almost two hundred years after the

date of Galileo's dialogue. But this, of course, is in no sense a guide

to the state of general opinion regarding the theory. We shall gain a

true gauge as to this if we assume that the greater number of important

thinkers had accepted the heliocentric doctrine before the middle of the

seventeenth century, and that before the close of that century the old

Ptolemaic idea had been quite abandoned. A wonderful revolution in

man's estimate of the universe had thus been effected within about two

centuries after the birth of Copernicus.

V. GALILEO AND THE NEW PHYSICS

After Galileo had felt the strong hand of the Inquisition, in 1632, he

was careful to confine his researches, or at least his publications, to

topics that seemed free from theological implications. In doing so he

reverted to the field of his earliest studies--namely, the field of

mechanics; and the Dialoghi delle Nuove Scienze, which he finished in

1636, and which was printed two years later, attained a celebrity no

less than that of the heretical dialogue that had preceded it. The

later work was free from all apparent heresies, yet perhaps it did

more towards the establishment of the Copernican doctrine, through

the teaching of correct mechanical principles, than the other work had

accomplished by a more direct method.

Galileo's astronomical discoveries were, as we have seen, in a sense

accidental; at least, they received their inception through the

inventive genius of another. His mechanical discoveries, on the other

hand, were the natural output of his own creative genius. At the very

beginning of his career, while yet a very young man, though a professor

of mathematics at Pisa, he had begun that onslaught upon the old

Aristotelian ideas which he was to continue throughout his life. At the

famous leaning tower in Pisa, the young iconoclast performed, in the

year 1590, one of the most theatrical demonstrations in the history

of science. Assembling a multitude of champions of the old ideas, he

proposed to demonstrate the falsity of the Aristotelian doctrine that

the velocity of falling bodies is proportionate to their weight. There

is perhaps no fact more strongly illustrative of the temper of

the Middle Ages than the fact that this doctrine, as taught by the

Aristotelian philosopher, should so long have gone unchallenged. Now,

however, it was put to the test; Galileo released a half-pound weight

and a hundred-pound cannon-ball from near the top of the tower, and,

needless to say, they reached the ground together. Of course, the

spectators were but little pleased with what they saw. They could not

doubt the evidence of their own senses as to the particular experiment

in question; they could suggest, however, that the experiment involved

a violation of the laws of nature through the practice of magic. To

controvert so firmly established an idea savored of heresy. The young

man guilty of such iconoclasm was naturally looked at askance by the

scholarship of his time. Instead of being applauded, he was hissed, and

he found it expedient presently to retire from Pisa.

Fortunately, however, the new spirit of progress had made itself felt

more effectively in some other portions of Italy, and so Galileo found a

refuge and a following in Padua, and afterwards in Florence; and while,

as we have seen, he was obliged to curb his enthusiasm regarding the

subject that was perhaps nearest his heart--the promulgation of the

Copernican theory--yet he was permitted in the main to carry on his

experimental observations unrestrained. These experiments gave him a

place of unquestioned authority among his contemporaries, and they have

transmitted his name to posterity as that of one of the greatest of

experimenters and the virtual founder of modern mechanical science. The

experiments in question range over a wide field; but for the most part

they have to do with moving bodies and with questions of force, or, as

we should now say, of energy. The experiment at the leaning tower showed

that the velocity of falling bodies is independent of the weight of the

bodies, provided the weight is sufficient to overcome the resistance

of the atmosphere. Later experiments with falling bodies led to the

discovery of laws regarding the accelerated velocity of fall. Such

velocities were found to bear a simple relation to the period of time

from the beginning of the fall. Other experiments, in which balls were

allowed to roll down inclined planes, corroborated the observation that

the pull of gravitation gave a velocity proportionate to the length of

fall, whether such fall were direct or in a slanting direction.

These studies were associated with observations on projectiles,

regarding which Galileo was the first to entertain correct notions.

According to the current idea, a projectile fired, for example, from a

cannon, moved in a straight horizontal line until the propulsive force

was exhausted, and then fell to the ground in a perpendicular line.

Galileo taught that the projectile begins to fall at once on leaving the

mouth of the cannon and traverses a parabolic course. According to his

idea, which is now familiar to every one, a cannon-ball dropped from the

level of the cannon's muzzle will strike the ground simultaneously with

a ball fired horizontally from the cannon. As to the paraboloid course

pursued by the projectile, the resistance of the air is a factor which

Galileo could not accurately compute, and which interferes with the

practical realization of his theory. But this is a minor consideration.

The great importance of his idea consists in the recognition that such

a force as that of gravitation acts in precisely the same way upon all

unsupported bodies, whether or not such bodies be at the same time acted

upon by a force of translation.

Out of these studies of moving bodies was gradually developed a correct

notion of several important general laws of mechanics--laws a knowledge

of which was absolutely essential to the progress of physical science.

The belief in the rotation of the earth made necessary a clear

conception that all bodies at the surface of the earth partake of that

motion quite independently of their various observed motions in relation

to one another. This idea was hard to grasp, as an oft-repeated argument

shows. It was asserted again and again that, if the earth rotates, a

stone dropped from the top of a tower could not fall at the foot of the

tower, since the earth's motion would sweep the tower far away from its

original position while the stone is in transit.

This was one of the stock arguments against the earth's motion, yet it

was one that could be refuted with the greatest ease by reasoning

from strictly analogous experiments. It might readily be observed, for

example, that a stone dropped from a moving cart does not strike the

ground directly below the point from which it is dropped, but partakes

of the forward motion of the cart. If any one doubt this he has but to

jump from a moving cart to be given a practical demonstration of the

fact that his entire body was in some way influenced by the motion of

translation. Similarly, the simple experiment of tossing a ball from the

deck of a moving ship will convince any one that the ball partakes of

the motion of the ship, so that it can be manipulated precisely as

if the manipulator were standing on the earth. In short, every-day

experience gives us illustrations of what might be called compound

motion, which makes it seem altogether plausible that, if the earth is

in motion, objects at its surface will partake of that motion in a way

that does not interfere with any other movements to which they may

be subjected. As the Copernican doctrine made its way, this idea of

compound motion naturally received more and more attention, and

such experiments as those of Galileo prepared the way for a new

interpretation of the mechanical principles involved.

The great difficulty was that the subject of moving bodies had all

along been contemplated from a wrong point of view. Since force must be

applied to an object to put it in motion, it was perhaps not unnaturally

assumed that similar force must continue to be applied to keep the

object in motion. When, for example, a stone is thrown from the hand,

the direct force applied necessarily ceases as soon as the projectile

leaves the hand. The stone, nevertheless, flies on for a certain

distance and then falls to the ground. How is this flight of the stone

to be explained? The ancient philosophers puzzled more than a little

over this problem, and the Aristotelians reached the conclusion that the

motion of the hand had imparted a propulsive motion to the air, and that

this propulsive motion was transmitted to the stone, pushing it on. Just

how the air took on this propulsive property was not explained, and

the vagueness of thought that characterized the time did not demand

an explanation. Possibly the dying away of ripples in water may have

furnished, by analogy, an explanation of the gradual dying out of the

impulse which propels the stone.

All of this was, of course, an unfortunate maladjustment of the point of

view. As every one nowadays knows, the air retards the progress of the

stone, enabling the pull of gravitation to drag it to the earth earlier

than it otherwise could. Were the resistance of the air and the pull of

gravitation removed, the stone as projected from the hand would fly on

in a straight line, at an unchanged velocity, forever. But this fact,

which is expressed in what we now term the first law of motion, was

extremely difficult to grasp. The first important step towards it was

perhaps implied in Galileo's study of falling bodies. These studies, as

we have seen, demonstrated that a half-pound weight and a hundred-pound

weight fall with the same velocity. It is, however, matter of common

experience that certain bodies, as, for example, feathers, do not

fall at the same rate of speed with these heavier bodies. This anomaly

demands an explanation, and the explanation is found in the resistance

offered the relatively light object by the air. Once the idea that the

air may thus act as an impeding force was grasped, the investigator of

mechanical principles had entered on a new and promising course.

Galileo could not demonstrate the retarding influence of air in the

way which became familiar a generation or two later; he could not put a

feather and a coin in a vacuum tube and prove that the two would there

fall with equal velocity, because, in his day, the air-pump had not yet

been invented. The experiment was made only a generation after the time

of Galileo, as we shall see; but, meantime, the great Italian had fully

grasped the idea that atmospheric resistance plays a most important part

in regard to the motion of falling and projected bodies. Thanks largely

to his own experiments, but partly also to the efforts of others, he had

come, before the end of his life, pretty definitely to realize that the

motion of a projectile, for example, must be thought of as inherent in

the projectile itself, and that the retardation or ultimate cessation of

that motion is due to the action of antagonistic forces. In other

words, he had come to grasp the meaning of the first law of motion. It

remained, however, for the great Frenchman Descartes to give precise

expression to this law two years after Galileo's death. As Descartes

expressed it in his Principia Philosophiae, published in 1644, any body

once in motion tends to go on in a straight line, at a uniform rate of

speed, forever. Contrariwise, a stationary body will remain forever at

rest unless acted on by some disturbing force.

This all-important law, which lies at the very foundation of all true

conceptions of mechanics, was thus worked out during the first half of

the seventeenth century, as the outcome of numberless experiments

for which Galileo's experiments with failing bodies furnished the

foundation. So numerous and so gradual were the steps by which the

reversal of view regarding moving bodies was effected that it is

impossible to trace them in detail. We must be content to reflect that

at the beginning of the Galilean epoch utterly false notions regarding

the subject were entertained by the very greatest philosophers--by

Galileo himself, for example, and by Kepler--whereas at the close of

that epoch the correct and highly illuminative view had been attained.

We must now consider some other experiments of Galileo which led to

scarcely less-important results. The experiments in question had to do

with the movements of bodies passing down an inclined plane, and

with the allied subject of the motion of a pendulum. The elaborate

experiments of Galileo regarding the former subject were made by

measuring the velocity of a ball rolling down a plane inclined at

various angles. He found that the velocity acquired by a ball was

proportional to the height from which the ball descended regardless of

the steepness of the incline. Experiments were made also with a ball

rolling down a curved gutter, the curve representing the are of a

circle. These experiments led to the study of the curvilinear motions of

a weight suspended by a cord; in other words, of the pendulum.

Regarding the motion of the pendulum, some very curious facts were soon

ascertained. Galileo found, for example, that a pendulum of a given

length performs its oscillations with the same frequency though the arc

described by the pendulum be varied greatly.(1) He found, also, that the

rate of oscillation for pendulums of different lengths varies according

to a simple law. In order that one pendulum shall oscillate one-half

as fast as another, the length of the pendulums must be as four to one.

Similarly, by lengthening the pendulums nine times, the oscillation

is reduced to one-third, In other words, the rate of oscillation of

pendulums varies inversely as the square of their length. Here, then, is

a simple relation between the motions of swinging bodies which suggests

the relation which Kepler bad discovered between the relative motions of

the planets. Every such discovery coming in this age of the rejuvenation

of experimental science had a peculiar force in teaching men the

all-important lesson that simple laws lie back of most of the diverse

phenomena of nature, if only these laws can be discovered.

Galileo further observed that his pendulum might be constructed of

any weight sufficiently heavy readily to overcome the atmospheric

resistance, and that, with this qualification, neither the weight nor

the material had any influence upon the time of oscillation, this being

solely determined by the length of the cord. Naturally, the practical

utility of these discoveries was not overlooked by Galileo. Since a

pendulum of a given length oscillates with unvarying rapidity, here is

an obvious means of measuring time. Galileo, however, appears not to

have met with any great measure of success in putting this idea into

practice. It remained for the mechanical ingenuity of Huyghens to

construct a satisfactory pendulum clock.

As a theoretical result of the studies of rolling and oscillating

bodies, there was developed what is usually spoken of as the third law

of motion--namely, the law that a given force operates upon a moving

body with an effect proportionate to its effect upon the same body when

at rest. Or, as Whewell states the law: "The dynamical effect of

force is as the statical effect; that is, the velocity which any

force generates in a given time, when it puts the body in motion, is

proportional to the pressure which this same force produces in a body

at rest."(2) According to the second law of motion, each one of the

different forces, operating at the same time upon a moving body,

produces the same effect as if it operated upon the body while at rest.

STEVINUS AND THE LAW OF EQUILIBRIUM

It appears, then, that the mechanical studies of Galileo, taken as a

whole, were nothing less than revolutionary. They constituted the first

great advance upon the dynamic studies of Archimedes, and then led to

the secure foundation for one of the most important of modern sciences.

We shall see that an important company of students entered the field

immediately after the time of Galileo, and carried forward the work he

had so well begun. But before passing on to the consideration of their

labors, we must consider work in allied fields of two men who were

contemporaries of Galileo and whose original labors were in some

respects scarcely less important than his own. These men are the

Dutchman Stevinus, who must always be remembered as a co-laborer with

Galileo in the foundation of the science of dynamics, and the Englishman

Gilbert, to whom is due the unqualified praise of first subjecting the

phenomenon of magnetism to a strictly scientific investigation.

Stevinus was born in the year 1548, and died in 1620. He was a man of a

practical genius, and he attracted the attention of his non-scientific

contemporaries, among other ways, by the construction of a curious

land-craft, which, mounted on wheels, was to be propelled by sails like

a boat. Not only did he write a book on this curious horseless carriage,

but he put his idea into practical application, producing a vehicle

which actually traversed the distance between Scheveningen and Petton,

with no fewer than twenty-seven passengers, one of them being Prince

Maurice of Orange. This demonstration was made about the year 1600. It

does not appear, however, that any important use was made of the strange

vehicle; but the man who invented it put his mechanical ingenuity

to other use with better effect. It was he who solved the problem of

oblique forces, and who discovered the important hydrostatic principle

that the pressure of fluids is proportionate to their depth, without

regard to the shape of the including vessel.

The study of oblique forces was made by Stevinus with the aid of

inclined planes. His most demonstrative experiment was a very simple

one, in which a chain of balls of equal weight was hung from a triangle;

the triangle being so constructed as to rest on a horizontal base, the

oblique sides bearing the relation to each other of two to one. Stevinus

found that his chain of balls just balanced when four balls were on the

longer side and two on the shorter and steeper side. The balancing of

force thus brought about constituted a stable equilibrium, Stevinus

being the first to discriminate between such a condition and the

unbalanced condition called unstable equilibrium. By this simple

experiment was laid the foundation of the science of statics. Stevinus

had a full grasp of the principle which his experiment involved, and he

applied it to the solution of oblique forces in all directions. Earlier

investigations of Stevinus were published in 1608. His collected works

were published at Leyden in 1634.

This study of the equilibrium of pressure of bodies at rest led

Stevinus, not unnaturally, to consider the allied subject of the

pressure of liquids. He is to be credited with the explanation of the

so-called hydrostatic paradox. The familiar modern experiment which

illustrates this paradox is made by inserting a long perpendicular tube

of small caliber into the top of a tight barrel. On filling the barrel

and tube with water, it is possible to produce a pressure which will

burst the barrel, though it be a strong one, and though the actual

weight of water in the tube is comparatively insignificant. This

illustrates the fact that the pressure at the bottom of a column of

liquid is proportionate to the height of the column, and not to its

bulk, this being the hydrostatic paradox in question. The explanation

is that an enclosed fluid under pressure exerts an equal force upon all

parts of the circumscribing wall; the aggregate pressure may, therefore,

be increased indefinitely by increasing the surface. It is this

principle, of course, which is utilized in the familiar hydrostatic

press. Theoretical explanations of the pressure of liquids were supplied

a generation or two later by numerous investigators, including Newton,

but the practical refoundation of the science of hydrostatics in modern

times dates from the experiments of Stevinus.

GALILEO AND THE EQUILIBRIUM OF FLUIDS

Experiments of an allied character, having to do with the equilibrium of

fluids, exercised the ingenuity of Galileo. Some of his most interesting

experiments have to do with the subject of floating bodies. It will be

recalled that Archimedes, away back in the Alexandrian epoch, had solved

the most important problems of hydrostatic equilibrium. Now, however,

his experiments were overlooked or forgotten, and Galileo was obliged

to make experiments anew, and to combat fallacious views that ought long

since to have been abandoned. Perhaps the most illuminative view of

the spirit of the times can be gained by quoting at length a paper of

Galileo's, in which he details his own experiments with floating bodies

and controverts the views of his opponents. The paper has further

value as illustrating Galileo's methods both as experimenter and as

speculative reasoner.

The current view, which Galileo here undertakes to refute, asserts that

water offers resistance to penetration, and that this resistance is

instrumental in determining whether a body placed in water will float

or sink. Galileo contends that water is non-resistant, and that bodies

float or sink in virtue of their respective weights. This, of course, is

merely a restatement of the law of Archimedes. But it remains to explain

the fact that bodies of a certain shape will float, while bodies of the

same material and weight, but of a different shape, will sink. We shall

see what explanation Galileo finds of this anomaly as we proceed.

In the first place, Galileo makes a cone of wood or of wax, and shows

that when it floats with either its point or its base in the water, it

displaces exactly the same amount of fluid, although the apex is by its

shape better adapted to overcome the resistance of the water, if that

were the cause of buoyancy. Again, the experiment may be varied by

tempering the wax with filings of lead till it sinks in the water, when

it will be found that in any figure the same quantity of cork must be

added to it to raise the surface.

"But," says Galileo, "this silences not my antagonists; they say that

all the discourse hitherto made by me imports little to them, and that

it serves their turn; that they have demonstrated in one instance, and

in such manner and figure as pleases them best--namely, in a board

and in a ball of ebony--that one when put into the water sinks to the

bottom, and that the other stays to swim on the top; and the matter

being the same, and the two bodies differing in nothing but in figure,

they affirm that with all perspicuity they have demonstrated and

sensibly manifested what they undertook. Nevertheless, I believe, and

think I can prove, that this very experiment proves nothing against my

theory. And first, it is false that the ball sinks and the board not;

for the board will sink, too, if you do to both the figures as the words

of our question require; that is, if you put them both in the water; for

to be in the water implies to be placed in the water, and by Aristotle's

own definition of place, to be placed imports to be environed by the

surface of the ambient body; but when my antagonists show the floating

board of ebony, they put it not into the water, but upon the water;

where, being detained by a certain impediment (of which more anon), it

is surrounded, partly with water, partly with air, which is contrary to

our agreement, for that was that bodies should be in the water, and not

part in the water, part in the air.

"I will not omit another reason, founded also upon experience, and, if

I deceive not myself, conclusive against the notion that figure, and

the resistance of the water to penetration, have anything to do with

the buoyancy of bodies. Choose a piece of wood or other matter, as,

for instance, walnut-wood, of which a ball rises from the bottom of the

water to the surface more slowly than a ball of ebony of the same

size sinks, so that, clearly, the ball of ebony divides the water more

readily in sinking than the ball of wood does in rising. Then take

a board of walnut-tree equal to and like the floating one of my

antagonists; and if it be true that this latter floats by reason of the

figure being unable to penetrate the water, the other of walnut-tree,

without a question, if thrust to the bottom, ought to stay there, as

having the same impeding figure, and being less apt to overcome the said

resistance of the water. But if we find by experience that not only the

thin board, but every other figure of the same walnut-tree, will return

to float, as unquestionably we shall, then I must desire my opponents

to forbear to attribute the floating of the ebony to the figure of the

board, since the resistance of the water is the same in rising as in

sinking, and the force of ascension of the walnut-tree is less than the

ebony's force for going to the bottom.

"Now let us return to the thin plate of gold or silver, or the thin

board of ebony, and let us lay it lightly upon the water, so that it may

stay there without sinking, and carefully observe the effect. It will

appear clearly that the plates are a considerable matter lower than the

surface of the water, which rises up and makes a kind of rampart round

them on every side. But if it has already penetrated and overcome the

continuity of the water, and is of its own nature heavier than the

water, why does it not continue to sink, but stop and suspend itself in

that little dimple that its weight has made in the water? My answer is,

because in sinking till its surface is below the water, which rises up

in a bank round it, it draws after and carries along with it the air

above it, so that that which, in this case, descends in the water is not

only the board of ebony or the plate of iron, but a compound of ebony

and air, from which composition results a solid no longer specifically

heavier than the water, as was the ebony or gold alone. But, gentlemen,

we want the same matter; you are to alter nothing but the shape, and,

therefore, have the goodness to remove this air, which may be done

simply by washing the surface of the board, for the water having once

got between the board and the air will run together, and the ebony will

go to the bottom; and if it does not, you have won the day.

"But methinks I hear some of my antagonists cunningly opposing this, and

telling me that they will not on any account allow their boards to be

wetted, because the weight of the water so added, by making it heavier

than it was before, draws it to the bottom, and that the addition of new

weight is contrary to our agreement, which was that the matter should be

the same.

"To this I answer, first, that nobody can suppose bodies to be put into

the water without their being wet, nor do I wish to do more to the board

than you may do to the ball. Moreover, it is not true that the board

sinks on account of the weight of the water added in the washing; for I

will put ten or twenty drops on the floating board, and so long as they

stand separate it shall not sink; but if the board be taken out and all

that water wiped off, and the whole surface bathed with one single drop,

and put it again upon the water, there is no question but it will sink,

the other water running to cover it, being no longer hindered by the

air. In the next place, it is altogether false that water can in any way

increase the weight of bodies immersed in it, for water has no weight in

water, since it does not sink. Now just as he who should say that brass

by its own nature sinks, but that when formed into the shape of a

kettle it acquires from that figure the virtue of lying in water without

sinking, would say what is false, because that is not purely brass which

then is put into the water, but a compound of brass and air; so is it

neither more nor less false that a thin plate of brass or ebony swims by

virtue of its dilated and broad figure. Also, I cannot omit to tell

my opponents that this conceit of refusing to bathe the surface of the

board might beget an opinion in a third person of a poverty of argument

on their side, especially as the conversation began about flakes of ice,

in which it would be simple to require that the surfaces should be kept

dry; not to mention that such pieces of ice, whether wet or dry, always

float, and so my antagonists say, because of their shape.

"Some may wonder that I affirm this power to be in the air of keeping

plate of brass or silver above water, as if in a certain sense I would

attribute to the air a kind of magnetic virtue for sustaining heavy

bodies with which it is in contact. To satisfy all these doubts I have

contrived the following experiment to demonstrate how truly the air does

support these bodies; for I have found, when one of these bodies which

floats when placed lightly on the water is thoroughly bathed and sunk to

the bottom, that by carrying down to it a little air without otherwise

touching it in the least, I am able to raise and carry it back to the

top, where it floats as before. To this effect, I take a ball of wax,

and with a little lead make it just heavy enough to sink very slowly to

the bottom, taking care that its surface be quite smooth and even. This,

if put gently into the water, submerges almost entirely, there remaining

visible only a little of the very top, which, so long as it is joined to

the air, keeps the ball afloat; but if we take away the contact of the

air by wetting this top, the ball sinks to the bottom and remains there.

Now to make it return to the surface by virtue of the air which before

sustained it, thrust into the water a glass with the mouth downward,

which will carry with it the air it contains, and move this down towards

the ball until you see, by the transparency of the glass, that the air

has reached the top of it; then gently draw the glass upward, and you

will see the ball rise, and afterwards stay on the top of the water,

if you carefully part the glass and water without too much disturbing

it."(3)

It will be seen that Galileo, while holding in the main to a correct

thesis, yet mingles with it some false ideas. At the very outset, of

course, it is not true that water has no resistance to penetration; it

is true, however, in the sense in which Galileo uses the term--that

is to say, the resistance of the water to penetration is not the

determining factor ordinarily in deciding whether a body sinks

or floats. Yet in the case of the flat body it is not altogether

inappropriate to say that the water resists penetration and thus

supports the body. The modern physicist explains the phenomenon as due

to surface-tension of the fluid. Of course, Galileo's disquisition

on the mixing of air with the floating body is utterly fanciful. His

experiments were beautifully exact; his theorizing from them was, in

this instance, altogether fallacious. Thus, as already intimated, his

paper is admirably adapted to convey a double lesson to the student of

science.

WILLIAM GILBERT AND THE STUDY OF MAGNETISM

It will be observed that the studies of Galileo and Stevinus were

chiefly concerned with the force of gravitation. Meanwhile, there was

an English philosopher of corresponding genius, whose attention was

directed towards investigation of the equally mysterious force of

terrestrial magnetism. With the doubtful exception of Bacon, Gilbert

was the most distinguished man of science in England during the reign

of Queen Elizabeth. He was for many years court physician, and Queen

Elizabeth ultimately settled upon him a pension that enabled him to

continue his researches in pure science.

His investigations in chemistry, although supposed to be of great

importance, are mostly lost; but his great work, De Magnete, on which

he labored for upwards of eighteen years, is a work of sufficient

importance, as Hallam says, "to raise a lasting reputation for its

author." From its first appearance it created a profound impression upon

the learned men of the continent, although in England Gilbert's theories

seem to have been somewhat less favorably received. Galileo freely

expressed his admiration for the work and its author; Bacon, who admired

the author, did not express the same admiration for his theories;

but Dr. Priestley, later, declared him to be "the father of modern

electricity."

Strangely enough, Gilbert's book had never been translated into English,

or apparently into any other language, until recent years, although at

the time of its publication certain learned men, unable to read the

book in the original, had asked that it should be. By this neglect, or

oversight, a great number of general readers as well as many scientists,

through succeeding centuries, have been deprived of the benefit of

writings that contained a good share of the fundamental facts about

magnetism as known to-day.

Gilbert was the first to discover that the earth is a great magnet, and

he not only gave the name of "pole" to the extremities of the magnetic

needle, but also spoke of these "poles" as north and south pole,

although he used these names in the opposite sense from that in which we

now use them, his south pole being the extremity which pointed towards

the north, and vice versa. He was also first to make use of the terms

"electric force," "electric emanations," and "electric attractions."

It is hardly necessary to say that some of the views taken by Gilbert,

many of his theories, and the accuracy of some of his experiments

have in recent times been found to be erroneous. As a pioneer in an

unexplored field of science, however, his work is remarkably accurate.

"On the whole," says Dr. John Robinson, "this performance contains more

real information than any writing of the age in which he lived, and is

scarcely exceeded by any that has appeared since."(4)

In the preface to his work Gilbert says: "Since in the discovery of

secret things, and in the investigation of hidden causes, stronger

reasons are obtained from sure experiments and demonstrated arguments

than from probable conjectures and the opinions of philosophical

speculators of the common sort, therefore, to the end of that noble

substance of that great loadstone, our common mother (the earth), still

quite unknown, and also that the forces extraordinary and exalted of

this globe may the better be understood, we have decided, first, to

begin with the common stony and ferruginous matter, and magnetic bodies,

and the part of the earth that we may handle and may perceive with

senses, and then to proceed with plain magnetic experiments, and to

penetrate to the inner parts of the earth."(5)

Before taking up the demonstration that the earth is simply a giant

loadstone, Gilbert demonstrated in an ingenious way that every

loadstone, of whatever size, has definite and fixed poles. He did this

by placing the stone in a metal lathe and converting it into a sphere,

and upon this sphere demonstrated how the poles can be found. To this

round loadstone he gave the name of terrella--that is, little earth.

"To find, then, poles answering to the earth," he says, "take in your

hand the round stone, and lay on it a needle or a piece of iron wire:

the ends of the wire move round their middle point, and suddenly come

to a standstill. Now, with ochre or with chalk, mark where the wire lies

still and sticks. Then move the middle or centre of the wire to another

spot, and so to a third and fourth, always marking the stone along

the length of the wire where it stands still; the lines so marked will

exhibit meridian circles, or circles like meridians, on the stone or

terrella; and manifestly they will all come together at the poles of the

stone. The circle being continued in this way, the poles appear, both

the north and the south, and betwixt these, midway, we may draw a large

circle for an equator, as is done by the astronomer in the heavens and

on his spheres, and by the geographer on the terrestrial globe."(6)

Gilbert had tried the familiar experiment of placing the loadstone on a

float in water, and observed that the poles always revolved until

they pointed north and south, which he explained as due to the earth's

magnetic attraction. In this same connection he noticed that a piece of

wrought iron mounted on a cork float was attracted by other metals to

a slight degree, and he observed also that an ordinary iron bar, if

suspended horizontally by a thread, assumes invariably a north and

south direction. These, with many other experiments of a similar nature,

convinced him that the earth "is a magnet and a loadstone," which he

says is a "new and till now unheard-of view of the earth."

Fully to appreciate Gilbert's revolutionary views concerning the earth

as a magnet, it should be remembered that numberless theories to explain

the action of the electric needle had been advanced. Columbus and

Paracelsus, for example, believed that the magnet was attracted by some

point in the heavens, such as a magnetic star. Gilbert himself tells of

some of the beliefs that had been held by his predecessors, many of whom

he declares "wilfully falsify." One of his first steps was to refute

by experiment such assertions as that of Cardan, that "a wound by a

magnetized needle was painless"; and also the assertion of Fracastoni

that loadstone attracts silver; or that of Scalinger, that the diamond

will attract iron; and the statement of Matthiolus that "iron rubbed

with garlic is no longer attracted to the loadstone."

Gilbert made extensive experiments to explain the dipping of the needle,

which had been first noticed by William Norman. His deduction as to

this phenomenon led him to believe that this was also explained by the

magnetic attraction of the earth, and to predict where the vertical dip

would be found. These deductions seem the more wonderful because at the

time he made them the dip had just been discovered, and had not been

studied except at London. His theory of the dip was, therefore, a

scientific prediction, based on a preconceived hypothesis. Gilbert found

the dip to be 72 degrees at London; eight years later Hudson found the

dip at 75 degrees 22' north latitude to be 89 degrees 30'; but it was

not until over two hundred years later, in 1831, that the vertical

dip was first observed by Sir James Ross at about 70 degrees 5' north

latitude, and 96 degrees 43' west longitude. This was not the exact

point assumed by Gilbert, and his scientific predictions, therefore,

were not quite correct; but such comparatively slight and excusable

errors mar but little the excellence of his work as a whole.

A brief epitome of some of his other important discoveries suffices

to show that the exalted position in science accorded him by

contemporaries, as well as succeeding generations of scientists,

was well merited. He was first to distinguish between magnetism

and electricity, giving the latter its name. He discovered also the

"electrical charge," and pointed the way to the discovery of insulation

by showing that the charge could be retained some time in the excited

body by covering it with some non-conducting substance, such as silk;

although, of course, electrical conduction can hardly be said to have

been more than vaguely surmised, if understood at all by him. The first

electrical instrument ever made, and known as such, was invented by him,

as was also the first magnetometer, and the first electrical indicating

device. Although three centuries have elapsed since his death, the

method of magnetizing iron first introduced by him is in common use

to-day.

He made exhaustive experiments with a needle balanced on a pivot to see

how many substances he could find which, like amber, on being rubbed

affected the needle. In this way he discovered that light substances

were attracted by alum, mica, arsenic, sealing-wax, lac sulphur, slags,

beryl, amethyst, rock-crystal, sapphire, jet, carbuncle, diamond,

opal, Bristol stone, glass, glass of antimony, gum-mastic, hard resin,

rock-salt, and, of course, amber. He discovered also that atmospheric

conditions affected the production of electricity, dryness being

unfavorable and moisture favorable.

Galileo's estimate of this first electrician is the verdict of

succeeding generations. "I extremely admire and envy this author," he

said. "I think him worthy of the greatest praise for the many new and

true observations which he has made, to the disgrace of so many vain and

fabling authors."

STUDIES OF LIGHT, HEAT, AND ATMOSPHERIC PRESSURE

We have seen that Gilbert was by no means lacking in versatility, yet

the investigations upon which his fame is founded were all pursued along

one line, so that the father of magnetism may be considered one of the

earliest of specialists in physical science. Most workers of the time,

on the other band, extended their investigations in many directions. The

sum total of scientific knowledge of that day had not bulked so large as

to exclude the possibility that one man might master it all. So we find

a Galileo, for example, making revolutionary discoveries in astronomy,

and performing fundamental experiments in various fields of physics.

Galileo's great contemporary, Kepler, was almost equally versatile,

though his astronomical studies were of such pre-eminent importance

that his other investigations sink into relative insignificance. Yet

he performed some notable experiments in at least one department of

physics. These experiments had to do with the refraction of light, a

subject which Kepler was led to investigate, in part at least, through

his interest in the telescope.

We have seen that Ptolemy in the Alexandrian time, and Alhazen, the

Arab, made studies of refraction. Kepler repeated their experiments,

and, striving as always to generalize his observations, he attempted to

find the law that governed the observed change of direction which a ray

of light assumes in passing from one medium to another. Kepler measured

the angle of refraction by means of a simple yet ingenious trough-like

apparatus which enabled him to compare readily the direct and refracted

rays. He discovered that when a ray of light passes through a glass

plate, if it strikes the farther surface of the glass at an angle

greater than 45 degrees it will be totally refracted instead of passing

through into the air. He could not well fail to know that different

mediums refract light differently, and that for the same medium the

amount of light valies with the change in the angle of incidence. He was

not able, however, to generalize his observations as he desired, and to

the last the law that governs refraction escaped him. It remained for

Willebrord Snell, a Dutchman, about the year 1621, to discover the

law in question, and for Descartes, a little later, to formulate it.

Descartes, indeed, has sometimes been supposed to be the discoverer of

the law. There is reason to believe that he based his generalizations

on the experiment of Snell, though he did not openly acknowledge his

indebtedness. The law, as Descartes expressed it, states that the sine

of the angle of incidence bears a fixed ratio to the sine of the angle

of refraction for any given medium. Here, then, was another illustration

of the fact that almost infinitely varied phenomena may be brought

within the scope of a simple law. Once the law had been expressed, it

could be tested and verified with the greatest ease; and, as usual, the

discovery being made, it seems surprising that earlier investigators--in

particular so sagacious a guesser as Kepler--should have missed it.

Galileo himself must have been to some extent a student of light, since,

as we have seen, he made such notable contributions to practical

optics through perfecting the telescope; but he seems not to have added

anything to the theory of light. The subject of heat, however, attracted

his attention in a somewhat different way, and he was led to the

invention of the first contrivance for measuring temperatures. His

thermometer was based on the afterwards familiar principle of the

expansion of a liquid under the influence of heat; but as a practical

means of measuring temperature it was a very crude affair, because the

tube that contained the measuring liquid was exposed to the air, hence

barometric changes of pressure vitiated the experiment. It remained for

Galileo's Italian successors of the Accademia del Cimento of Florence

to improve upon the apparatus, after the experiments of Torricelli--to

which we shall refer in a moment--had thrown new light on the question

of atmospheric pressure. Still later the celebrated Huygens hit upon the

idea of using the melting and the boiling point of water as fixed

points in a scale of measurements, which first gave definiteness to

thermometric tests.

TORRICELLI

In the closing years of his life Galileo took into his family, as

his adopted disciple in science, a young man, Evangelista Torricelli

(1608-1647), who proved himself, during his short lifetime, to be a

worthy follower of his great master. Not only worthy on account of his

great scientific discoveries, but grateful as well, for when he had

made the great discovery that the "suction" made by a vacuum was really

nothing but air pressure, and not suction at all, he regretted that

so important a step in science might not have been made by his

great teacher, Galileo, instead of by himself. "This generosity of

Torricelli," says Playfair, "was, perhaps, rarer than his genius: there

are more who might have discovered the suspension of mercury in the

barometer than who would have been willing to part with the honor of the

discovery to a master or a friend."

Torricelli's discovery was made in 1643, less than two years after the

death of his master. Galileo had observed that water will not rise in

an exhausted tube, such as a pump, to a height greater than thirty-three

feet, but he was never able to offer a satisfactory explanation of the

principle. Torricelli was able to demonstrate that the height at which

the water stood depended upon nothing but its weight as compared with

the weight of air. If this be true, it is evident that any fluid will

be supported at a definite height, according to its relative weight

as compared with air. Thus mercury, which is about thirteen times more

dense than water, should only rise to one-thirteenth the height of a

column of water--that is, about thirty inches. Reasoning in this way,

Torricelli proceeded to prove that his theory was correct. Filling a

long tube, closed at one end, with mercury, he inverted the tube with

its open orifice in a vessel of mercury. The column of mercury fell at

once, but at a height of about thirty inches it stopped and remained

stationary, the pressure of the air on the mercury in the vessel

maintaining it at that height. This discovery was a shattering blow

to the old theory that had dominated that field of physics for so many

centuries. It was completely revolutionary to prove that, instead of

a mysterious something within the tube being responsible for the

suspension of liquids at certain heights, it was simply the ordinary

atmospheric pressure mysterious enough, it is true--pushing upon them

from without. The pressure exerted by the atmosphere was but little

understood at that time, but Torricelli's discovery aided materially

in solving the mystery. The whole class of similar phenomena of air

pressure, which had been held in the trammel of long-established but

false doctrines, was now reduced to one simple law, and the door to a

solution of a host of unsolved problems thrown open.

It had long been suspected and believed that the density of the

atmosphere varies at certain times. That the air is sometimes "heavy"

and at other times "light" is apparent to the senses without scientific

apparatus for demonstration. It is evident, then, that Torricelli's

column of mercury should rise and fall just in proportion to the

lightness or heaviness of the air. A short series of observations

proved that it did so, and with those observations went naturally

the observations as to changes in the weather. It was only necessary,

therefore, to scratch a scale on the glass tube, indicating relative

atmospheric pressures, and the Torricellian barometer was complete.

Such a revolutionary theory and such an important discovery were, of

course, not to be accepted without controversy, but the feeble arguments

of the opponents showed how untenable the old theory had become. In

1648 Pascal suggested that if the theory of the pressure of air upon the

mercury was correct, it could be demonstrated by ascending a mountain

with the mercury tube. As the air was known to get progressively lighter

from base to summit, the height of the column should be progressively

lessened as the ascent was made, and increase again on the descent

into the denser air. The experiment was made on the mountain called

the Puy-de-Dome, in Auvergne, and the column of mercury fell and rose

progressively through a space of about three inches as the ascent and

descent were made.

This experiment practically sealed the verdict on the new theory, but

it also suggested something more. If the mercury descended to a certain

mark on the scale on a mountain-top whose height was known, why was not

this a means of measuring the heights of all other elevations? And so

the beginning was made which, with certain modifications and corrections

in details, is now the basis of barometrical measurements of heights.

In hydraulics, also, Torricelli seems to have taken one of the first

steps. He did this by showing that the water which issues from a hole

in the side or bottom of a vessel does so at the same velocity as that

which a body would acquire by falling from the level of the surface of

the water to that of the orifice. This discovery was of the greatest

importance to a correct understanding of the science of the motions of

fluids. He also discovered the valuable mechanical principle that if any

number of bodies be connected so that by their motion there is neither

ascent nor descent of their centre of gravity, these bodies are in

equilibrium.

Besides making these discoveries, he greatly improved the microscope

and the telescope, and invented a simple microscope made of a globule of

glass. In 1644 he published a tract on the properties of the cycloid in

which he suggested a solution of the problem of its quadrature. As soon

as this pamphlet appeared its author was accused by Gilles Roberval

(1602-1675) of having appropriated a solution already offered by him.

This led to a long debate, during which Torricelli was seized with a

fever, from the effects of which he died, in Florence, October 25, 1647.

There is reason to believe, however, that while Roberval's discovery

was made before Torricelli's, the latter reached his conclusions

independently.

VI. TWO PSEUDO-SCIENCES--ALCHEMY AND ASTROLOGY

In recent chapters we have seen science come forward with tremendous

strides. A new era is obviously at hand. But we shall misconceive the

spirit of the times if we fail to understand that in the midst of all

this progress there was still room for mediaeval superstition and for

the pursuit of fallacious ideals. Two forms of pseudo-science were

peculiarly prevalent--alchemy and astrology. Neither of these can with

full propriety be called a science, yet both were pursued by many of the

greatest scientific workers of the period. Moreover, the studies of the

alchemist may with some propriety be said to have laid the foundation

for the latter-day science of chemistry; while astrology was closely

allied to astronomy, though its relations to that science are not as

intimate as has sometimes been supposed.

Just when the study of alchemy began is undetermined. It was certainly

of very ancient origin, perhaps Egyptian, but its most flourishing time

was from about the eighth century A.D. to the eighteenth century. The

stories of the Old Testament formed a basis for some of the

strange beliefs regarding the properties of the magic "elixir,"

or "philosopher's stone." Alchemists believed that most of the

antediluvians, perhaps all of them, possessed a knowledge of this stone.

How, otherwise, could they have prolonged their lives to nine and a half

centuries? And Moses was surely a first-rate alchemist, as is proved by

the story of the Golden Calf.(1) After Aaron had made the calf of gold,

Moses performed the much more difficult task of grinding it to powder

and "strewing it upon the waters," thus showing that he had transmuted

it into some lighter substance.

But antediluvians and Biblical characters were not the only persons who

were thought to have discovered the coveted "elixir." Hundreds of aged

mediaeval chemists were credited with having made the discovery, and

were thought to be living on through the centuries by its means. Alaies

de Lisle, for example, who died in 1298, at the age of 110, was alleged

to have been at the point of death at the age of fifty, but just at

this time he made the fortunate discovery of the magic stone, and so

continued to live in health and affluence for sixty years more. And De

Lisle was but one case among hundreds.

An aged and wealthy alchemist could claim with seeming plausibility that

he was prolonging his life by his magic; whereas a younger man might

assert that, knowing the great secret, he was keeping himself young

through the centuries. In either case such a statement, or rumor, about

a learned and wealthy alchemist was likely to be believed, particularly

among strangers; and as such a man would, of course, be the object

of much attention, the claim was frequently made by persons seeking

notoriety. One of the most celebrated of these impostors was a certain

Count de Saint-Germain, who was connected with the court of Louis XV.

His statements carried the more weight because, having apparently no

means of maintenance, he continued to live in affluence year after

year--for two thousand years, as he himself admitted--by means of the

magic stone. If at any time his statements were doubted, he was in the

habit of referring to his valet for confirmation, this valet being also

under the influence of the elixir of life.

"Upon one occasion his master was telling a party of ladies and

gentlemen, at dinner, some conversation he had had in Palestine, with

King Richard I., of England, whom he described as a very particular

friend of his. Signs of astonishment and incredulity were visible on the

faces of the company, upon which Saint-Germain very coolly turned to his

servant, who stood behind his chair, and asked him if he had not spoken

the truth. 'I really cannot say,' replied the man, without moving a

muscle; 'you forget, sir, I have been only five hundred years in your

service.' 'Ah, true,' said his master, 'I remember now; it was a little

before your time!'"(2)

In the time of Saint-Germain, only a little over a century ago, belief

in alchemy had almost disappeared, and his extraordinary tales were

probably regarded in the light of amusing stories. Still there was

undoubtedly a lingering suspicion in the minds of many that this man

possessed some peculiar secret. A few centuries earlier his tales

would hardly have been questioned, for at that time the belief in the

existence of this magic something was so strong that the search for it

became almost a form of mania; and once a man was seized with it, lie

gambled away health, position, and life itself in pursuing the coveted

stake. An example of this is seen in Albertus Magnus, one of the most

learned men of his time, who it is said resigned his position as bishop

of Ratisbon in order that he might pursue his researches in alchemy.

If self-sacrifice was not sufficient to secure the prize, crime would

naturally follow, for there could be no limit to the price of the

stakes in this game. The notorious Marechal de Reys, failing to find the

coveted stone by ordinary methods of laboratory research, was persuaded

by an impostor that if he would propitiate the friendship of the

devil the secret would be revealed. To this end De Reys began secretly

capturing young children as they passed his castle and murdering

them. When he was at last brought to justice it was proved that he had

murdered something like a hundred children within a period of three

years. So, at least, runs one version of the story of this perverted

being.

Naturally monarchs, constantly in need of funds, were interested in

these alchemists. Even sober England did not escape, and Raymond

Lully, one of the most famous of the thirteenth and fourteenth century

alchemists, is said to have been secretly invited by King Edward I. (or

II.) to leave Milan and settle in England. According to some accounts,

apartments were assigned to his use in the Tower of London, where he is

alleged to have made some six million pounds sterling for the monarch,

out of iron, mercury, lead, and pewter.

Pope John XXII., a friend and pupil of the alchemist Arnold de

Villeneuve, is reported to have learned the secrets of alchemy from

his master. Later he issued two bulls against "pretenders" in the art,

which, far from showing his disbelief, were cited by alchemists as

proving that he recognized pretenders as distinct from true masters of

magic.

To moderns the attitude of mind of the alchemist is difficult to

comprehend. It is, perhaps, possible to conceive of animals or plants

possessing souls, but the early alchemist attributed the same thing--or

something kin to it--to metals also. Furthermore, just as plants

germinated from seeds, so metals were supposed to germinate also, and

hence a constant growth of metals in the ground. To prove this the

alchemist cited cases where previously exhausted gold-mines were found,

after a lapse of time, to contain fresh quantities of gold. The "seed"

of the remaining particles of gold had multiplied and increased.

But this germinating process could only take place under favorable

conditions, just as the seed of a plant must have its proper

surroundings before germinating; and it was believed that the action of

the philosopher's stone was to hasten this process, as man may hasten

the growth of plants by artificial means. Gold was looked upon as the

most perfect metal, and all other metals imperfect, because not yet

"purified." By some alchemists they were regarded as lepers, who, when

cured of their leprosy, would become gold. And since nature intended

that all things should be perfect, it was the aim of the alchemist to

assist her in this purifying process, and incidentally to gain wealth

and prolong his life.

By other alchemists the process of transition from baser metals into

gold was conceived to be like a process of ripening fruit. The ripened

product was gold, while the green fruit, in various stages of maturity,

was represented by the base metals. Silver, for example, was more nearly

ripe than lead; but the difference was only one of "digestion," and it

was thought that by further "digestion" lead might first become silver

and eventually gold. In other words, Nature had not completed her

work, and was wofully slow at it at best; but man, with his superior

faculties, was to hasten the process in his laboratories--if he could

but hit upon the right method of doing so.

It should not be inferred that the alchemist set about his task of

assisting nature in a haphazard way, and without training in the various

alchemic laboratory methods. On the contrary, he usually served a long

apprenticeship in the rudiments of his calling. He was obliged to learn,

in a general way, many of the same things that must be understood in

either chemical or alchemical laboratories. The general knowledge that

certain liquids vaporize at lower temperatures than others, and that

the melting-points of metals differ greatly, for example, was just

as necessary to alchemy as to chemistry. The knowledge of the gross

structure, or nature, of materials was much the same to the alchemist

as to the chemist, and, for that matter, many of the experiments in

calcining, distilling, etc., were practically identical.

To the alchemist there were three principles--salt, sulphur,

and mercury--and the sources of these principles were the four

elements--earth, water, fire, and air. These four elements were

accountable for every substance in nature. Some of the experiments to

prove this were so illusive, and yet apparently so simple, that one is

not surprised that it took centuries to disprove them. That water was

composed of earth and air seemed easily proven by the simple process of

boiling it in a tea-kettle, for the residue left was obviously an earthy

substance, whereas the steam driven off was supposed to be air. The

fact that pure water leaves no residue was not demonstrated until

after alchemy had practically ceased to exist. It was possible also to

demonstrate that water could be turned into fire by thrusting a red-hot

poker under a bellglass containing a dish of water. Not only did the

quantity of water diminish, but, if a lighted candle was thrust under

the glass, the contents ignited and burned, proving, apparently, that

water had been converted into fire. These, and scores of other similar

experiments, seemed so easily explained, and to accord so well with the

"four elements" theory, that they were seldom questioned until a later

age of inductive science.

But there was one experiment to which the alchemist pinned his faith in

showing that metals could be "killed" and "revived," when proper means

were employed. It had been known for many centuries that if any metal,

other than gold or silver, were calcined in an open crucible, it turned,

after a time, into a peculiar kind of ash. This ash was thought by the

alchemist to represent the death of the metal. But if to this same ash

a few grains of wheat were added and heat again applied to the crucible,

the metal was seen to "rise from its ashes" and resume its original

form--a well-known phenomenon of reducing metals from oxides by the

use of carbon, in the form of wheat, or, for that matter, any other

carbonaceous substance. Wheat was, therefore, made the symbol of the

resurrection of the life eternal. Oats, corn, or a piece of charcoal

would have "revived" the metals from the ashes equally well, but the

mediaeval alchemist seems not to have known this. However, in this

experiment the metal seemed actually to be destroyed and revivified,

and, as science had not as yet explained this striking phenomenon, it is

little wonder that it deceived the alchemist.

Since the alchemists pursued their search of the magic stone in such

a methodical way, it would seem that they must have some idea of

the appearance of the substance they sought. Probably they did, each

according to his own mental bias; but, if so, they seldom committed

themselves to writing, confining their discourses largely to

speculations as to the properties of this illusive substance.

Furthermore, the desire for secrecy would prevent them from expressing

so important a piece of information. But on the subject of the

properties, if not on the appearance of the "essence," they were

voluminous writers. It was supposed to be the only perfect substance

in existence, and to be confined in various substances, in quantities

proportionate to the state of perfection of the substance. Thus, gold

being most nearly perfect would contain more, silver less, lead still

less, and so on. The "essence" contained in the more nearly perfect

metals was thought to be more potent, a very small quantity of it being

capable of creating large quantities of gold and of prolonging life

indefinitely.

It would appear from many of the writings of the alchemists that their

conception of nature and the supernatural was so confused and entangled

in an inexplicable philosophy that they themselves did not really

understand the meaning of what they were attempting to convey. But it

should not be forgotten that alchemy was kept as much as possible from

the ignorant general public, and the alchemists themselves had knowledge

of secret words and expressions which conveyed a definite meaning to

one of their number, but which would appear a meaningless jumble to an

outsider. Some of these writers declared openly that their writings were

intended to convey an entirely erroneous impression, and were sent out

only for that purpose.

However, while it may have been true that the vagaries of their writings

were made purposely, the case is probably more correctly explained

by saying that the very nature of the art made definite statements

impossible. They were dealing with something that did not exist--could

not exist. Their attempted descriptions became, therefore, the language

of romance rather than the language of science.

But if the alchemists themselves were usually silent as to the

appearance of the actual substance of the philosopher's stone, there

were numberless other writers who were less reticent. By some it was

supposed to be a stone, by others a liquid or elixir, but more commonly

it was described as a black powder. It also possessed different degrees

of efficiency according to its degrees of purity, certain forms only

possessing the power of turning base metals into gold, while others

gave eternal youth and life or different degrees of health. Thus an

alchemist, who had made a partial discovery of this substance, could

prolong life a certain number of years only, or, possessing only a small

and inadequate amount of the magic powder, he was obliged to give up the

ghost when the effect of this small quantity had passed away.

This belief in the supernatural power of the philosopher's stone to

prolong life and heal diseases was probably a later phase of alchemy,

possibly developed by attempts to connect the power of the mysterious

essence with Biblical teachings. The early Roman alchemists, who claimed

to be able to transmute metals, seem not to have made other claims for

their magic stone.

By the fifteenth century the belief in the philosopher's stone had

become so fixed that governments began to be alarmed lest some lucky

possessor of the secret should flood the country with gold, thus

rendering the existing coin of little value. Some little consolation was

found in the thought that in case all the baser metals were converted

into gold iron would then become the "precious metal," and would remain

so until some new philosopher's stone was found to convert gold back

into iron--a much more difficult feat, it was thought. However, to be on

the safe side, the English Parliament, in 1404, saw fit to pass an act

declaring the making of gold and silver to be a felony. Nevertheless, in

1455, King Henry VI. granted permission to several "knights, citizens of

London, chemists, and monks" to find the philosopher's stone, or elixir,

that the crown might thus be enabled to pay off its debts. The monks

and ecclesiastics were supposed to be most likely to discover the secret

process, since "they were such good artists in transubstantiating bread

and wine."

In Germany the emperors Maximilian I., Rudolf II., and Frederick II.

gave considerable attention to the search, and the example they set was

followed by thousands of their subjects. It is said that some noblemen

developed the unpleasant custom of inviting to their courts men who

were reputed to have found the stone, and then imprisoning the poor

alchemists until they had made a certain quantity of gold, stimulating

their activity with tortures of the most atrocious kinds. Thus this

danger of being imprisoned and held for ransom until some fabulous

amount of gold should be made became the constant menace of the

alchemist. It was useless for an alchemist to plead poverty once it was

noised about that he had learned the secret. For how could such a man

be poor when, with a piece of metal and a few grains of magic powder,

he was able to provide himself with gold? It was, therefore, a reckless

alchemist indeed who dared boast that he had made the coveted discovery.

The fate of a certain indiscreet alchemist, supposed by many to have

been Seton, a Scotchman, was not an uncommon one. Word having been

brought to the elector of Saxony that this alchemist was in Dresden

and boasting of his powers, the elector caused him to be arrested and

imprisoned. Forty guards were stationed to see that he did not escape

and that no one visited him save the elector himself. For some time the

elector tried by argument and persuasion to penetrate his secret or to

induce him to make a certain quantity of gold; but as Seton steadily

refused, the rack was tried, and for several months he suffered torture,

until finally, reduced to a mere skeleton, he was rescued by a rival

candidate of the elector, a Pole named Michael Sendivogins, who drugged

the guards. However, before Seton could be "persuaded" by his new

captor, he died of his injuries.

But Sendivogins was also ambitious in alchemy, and, since Seton was

beyond his reach, he took the next best step and married his widow.

From her, as the story goes, he received an ounce of black powder--the

veritable philosopher's stone. With this he manufactured great

quantities of gold, even inviting Emperor Rudolf II. to see him work

the miracle. That monarch was so impressed that he caused a tablet to be

inserted in the wall of the room in which he had seen the gold made.

Sendivogins had learned discretion from the misfortune of Seton, so that

he took the precaution of concealing most of the precious powder in a

secret chamber of his carriage when he travelled, having only a small

quantity carried by his steward in a gold box. In particularly dangerous

places, he is said to have exchanged clothes with his coachman, making

the servant take his place in the carriage while he mounted the box.

About the middle of the seventeenth century alchemy took such firm root

in the religious field that it became the basis of the sect known as

the Rosicrucians. The name was derived from the teaching of a German

philosopher, Rosenkreutz, who, having been healed of a dangerous illness

by an Arabian supposed to possess the philosopher's stone, returned home

and gathered about him a chosen band of friends, to whom he imparted the

secret. This sect came rapidly into prominence, and for a short time at

least created a sensation in Europe, and at the time were credited

with having "refined and spiritualized" alchemy. But by the end of the

seventeenth century their number had dwindled to a mere handful, and

henceforth they exerted little influence.

Another and earlier religious sect was the Aureacrucians, founded by

Jacob Bohme, a shoemaker, born in Prussia in 1575. According to his

teachings the philosopher's stone could be discovered by a diligent

search of the Old and the New Testaments, and more particularly the

Apocalypse, which contained all the secrets of alchemy. This sect found

quite a number of followers during the life of Bohme, but gradually died

out after his death; not, however, until many of its members had been

tortured for heresy, and one at least, Kuhlmann, of Moscow, burned as a

sorcerer.

The names of the different substances that at various times were

thought to contain the large quantities of the "essence" during the many

centuries of searching for it, form a list of practically all substances

that were known, discovered, or invented during the period. Some

believed that acids contained the substance; others sought it in

minerals or in animal or vegetable products; while still others looked

to find it among the distilled "spirits"--the alcoholic liquors and

distilled products. On the introduction of alcohol by the Arabs that

substance became of all-absorbing interest, and for a long time allured

the alchemist into believing that through it they were soon to be

rewarded. They rectified and refined it until "sometimes it was so

strong that it broke the vessels containing it," but still it failed in

its magic power. Later, brandy was substituted for it, and this in turn

discarded for more recent discoveries.

There were always, of course, two classes of alchemists: serious

investigators whose honesty could not be questioned, and clever

impostors whose legerdemain was probably largely responsible for the

extended belief in the existence of the philosopher's stone. Sometimes

an alchemist practised both, using the profits of his sleight-of-hand to

procure the means of carrying on his serious alchemical researches. The

impostures of some of these jugglers deceived even the most intelligent

and learned men of the time, and so kept the flame of hope constantly

burning. The age of cold investigation had not arrived, and it is easy

to understand how an unscrupulous mediaeval Hermann or Kellar might

completely deceive even the most intelligent and thoughtful scholars.

In scoffing at the credulity of such an age, it should not be forgotten

that the "Keely motor" was a late nineteenth-century illusion.

But long before the belief in the philosopher's stone had died out, the

methods of the legerdemain alchemist had been investigated and reported

upon officially by bodies of men appointed to make such investigations,

although it took several generations completely to overthrow a

superstition that had been handed down through several thousand years.

In April of 1772 Monsieur Geoffroy made a report to the Royal Academy of

Sciences, at Paris, on the alchemic cheats principally of the sixteenth

and seventeenth centuries. In this report he explains many of the

seemingly marvellous feats of the unscrupulous alchemists. A very common

form of deception was the use of a double-bottomed crucible. A copper or

brass crucible was covered on the inside with a layer of wax, cleverly

painted so as to resemble the ordinary metal. Between this layer of wax

and the bottom of the crucible, however, was a layer of gold dust or

silver. When the alchemist wished to demonstrate his power, he had but

to place some mercury or whatever substance he chose in the crucible,

heat it, throw in a grain or two of some mysterious powder, pronounce a

few equally mysterious phrases to impress his audience, and, behold, a

lump of precious metal would be found in the bottom of his pot. This was

the favorite method of mediocre performers, but was, of course, easily

detected.

An equally successful but more difficult way was to insert

surreptitiously a lump of metal into the mixture, using an ordinary

crucible. This required great dexterity, but was facilitated by the

use of many mysterious ceremonies on the part of the operator while

performing, just as the modern vaudeville performer diverts the

attention of the audience to his right hand while his left is engaged

in the trick. Such ceremonies were not questioned, for it was the common

belief that the whole process "lay in the spirit as much as in the

substance," many, as we have seen, regarding the whole process as a

divine manifestation.

Sometimes a hollow rod was used for stirring the mixture in the

crucible, this rod containing gold dust, and having the end plugged

either with wax or soft metal that was easily melted. Again, pieces

of lead were used which had been plugged with lumps of gold carefully

covered over; and a very simple and impressive demonstration was making

use of a nugget of gold that had been coated over with quicksilver

and tarnished so as to resemble lead or some base metal. When this was

thrown into acid the coating was removed by chemical action, leaving the

shining metal in the bottom of the vessel. In order to perform some

of these tricks, it is obvious that the alchemist must have been well

supplied with gold, as some of them, when performing before a royal

audience, gave the products to their visitors. But it was always

a paying investment, for once his reputation was established the

gold-maker found an endless variety of ways of turning his alleged

knowledge to account, frequently amassing great wealth.

Some of the cleverest of the charlatans often invited royal or other

distinguished guests to bring with them iron nails to be turned into

gold ones. They were transmuted in the alchemist's crucible before the

eyes of the visitors, the juggler adroitly extracting the iron nail

and inserting a gold one without detection. It mattered little if the

converted gold nail differed in size and shape from the original, for

this change in shape could be laid to the process of transmutation;

and even the very critical were hardly likely to find fault with the

exchange thus made. Furthermore, it was believed that gold possessed the

property of changing its bulk under certain conditions, some of the

more conservative alchemists maintaining that gold was only increased in

bulk, not necessarily created, by certain forms of the magic stone. Thus

a very proficient operator was thought to be able to increase a grain

of gold into a pound of pure metal, while one less expert could only

double, or possibly treble, its original weight.

The actual number of useful discoveries resulting from the efforts of

the alchemists is considerable, some of them of incalculable value.

Roger Bacon, who lived in the thirteenth century, while devoting much

of his time to alchemy, made such valuable discoveries as the theory,

at least, of the telescope, and probably gunpowder. Of this latter

we cannot be sure that the discovery was his own and that he had not

learned of it through the source of old manuscripts. But it is not

impossible nor improbable that he may have hit upon the mixture that

makes the explosives while searching for the philosopher's stone in his

laboratory. "Von Helmont, in the same pursuit, discovered the properties

of gas," says Mackay; "Geber made discoveries in chemistry, which were

equally important; and Paracelsus, amid his perpetual visions of the

transmutation of metals, found that mercury was a remedy for one of

the most odious and excruciating of all the diseases that afflict

humanity."' As we shall see a little farther on, alchemy finally evolved

into modern chemistry, but not until it had passed through several

important transitional stages.

ASTROLOGY

In a general way modern astronomy may be considered as the outgrowth

of astrology, just as modern chemistry is the result of alchemy. It is

quite possible, however, that astronomy is the older of the two;

but astrology must have developed very shortly after. The primitive

astronomer, having acquired enough knowledge from his observations of

the heavenly bodies to make correct predictions, such as the time of the

coming of the new moon, would be led, naturally, to believe that

certain predictions other than purely astronomical ones could be made

by studying the heavens. Even if the astronomer himself did not believe

this, some of his superstitious admirers would; for to the unscientific

mind predictions of earthly events would surely seem no more miraculous

than correct predictions as to the future movements of the sun, moon,

and stars. When astronomy had reached a stage of development so that

such things as eclipses could be predicted with anything like accuracy,

the occult knowledge of the astronomer would be unquestioned. Turning

this apparently occult knowledge to account in a mercenary way would

then be the inevitable result, although it cannot be doubted that many

of the astrologers, in all ages, were sincere in their beliefs.

Later, as the business of astrology became a profitable one, sincere

astronomers would find it expedient to practise astrology as a means of

gaining a livelihood. Such a philosopher as Kepler freely admitted that

he practised astrology "to keep from starving," although he confessed

no faith in such predictions. "Ye otherwise philosophers," he said, "ye

censure this daughter of astronomy beyond her deserts; know ye not that

she must support her mother by her charms."

Once astrology had become an established practice, any considerable

knowledge of astronomy was unnecessary, for as it was at best but a

system of good guessing as to future events, clever impostors could

thrive equally well without troubling to study astronomy. The celebrated

astrologers, however, were usually astronomers as well, and undoubtedly

based many of their predictions on the position and movements of the

heavenly bodies. Thus, the casting of a horoscope that is, the methods

by which the astrologers ascertained the relative position of the

heavenly bodies at the time of a birth--was a simple but fairly exact

procedure. Its basis was the zodiac, or the path traced by the sun in

his yearly course through certain constellations. At the moment of

the birth of a child, the first care of the astrologer was to note the

particular part of the zodiac that appeared on the horizon. The zodiac

was then divided into "houses"--that is, into twelve spaces--on a chart.

In these houses were inserted the places of the planets, sun, and moon,

with reference to the zodiac. When this chart was completed it made a

fairly correct diagram of the heavens and the position of the heavenly

bodies as they would appear to a person standing at the place of birth

at a certain time.

Up to this point the process was a simple one of astronomy. But the next

step--the really important one--that of interpreting this chart, was the

one which called forth the skill and imagination of the astrologer. In

this interpretation, not in his mere observations, lay the secret of his

success. Nor did his task cease with simply foretelling future events

that were to happen in the life of the newly born infant. He must not

only point out the dangers, but show the means whereby they could be

averted, and his prophylactic measures, like his predictions, were

alleged to be based on his reading of the stars.

But casting a horoscope at the time of births was, of course, only a

small part of the astrologer's duty. His offices were sought by persons

of all ages for predictions as to their futures, the movements of an

enemy, where to find stolen goods, and a host of everyday occurrences.

In such cases it is more than probable that the astrologers did very

little consulting of the stars in making their predictions. They became

expert physiognomists and excellent judges of human nature, and were

thus able to foretell futures with the same shrewdness and by the same

methods as the modern "mediums," palmists, and fortune-tellers. To

strengthen belief in their powers, it became a common thing for some

supposedly lost document of the astrologer to be mysteriously discovered

after an important event, this document purporting to foretell this very

event. It was also a common practice with astrologers to retain, or have

access to, their original charts, cleverly altering them from time to

time to fit conditions.

The dangers attendant upon astrology were of such a nature that the lot

of the astrologer was likely to prove anything but an enviable one.

As in the case of the alchemist, the greater the reputation of an

astrologer the greater dangers he was likely to fall into. If he became

so famous that he was employed by kings or noblemen, his too true or

too false prophecies were likely to bring him into disrepute--even to

endanger his life.

Throughout the dark age the astrologers flourished, but the sixteenth

and seventeenth centuries were the golden age of these impostors. A

skilful astrologer was as much an essential to the government as the

highest official, and it would have been a bold monarch, indeed, who

would undertake any expedition of importance unless sanctioned by the

governing stars as interpreted by these officials.

It should not be understood, however, that belief in astrology died

with the advent of the Copernican doctrine. It did become separated

from astronomy very shortly after, to be sure, and undoubtedly among the

scientists it lost much of its prestige. But it cannot be considered

as entirely passed away, even to-day, and even if we leave out of

consideration street-corner "astrologers" and fortune-tellers, whose

signs may be seen in every large city, there still remains quite a large

class of relatively intelligent people who believe in what they call

"the science of astrology." Needless to say, such people are not found

among the scientific thinkers; but it is significant that scarcely a

year passes that some book or pamphlet is not published by some ardent

believer in astrology, attempting to prove by the illogical dogmas

characteristic of unscientific thinkers that astrology is a science. The

arguments contained in these pamphlets are very much the same as those

of the astrologers three hundred years ago, except that they lack the

quaint form of wording which is one of the features that lends interest

to the older documents. These pamphlets need not be taken seriously, but

they are interesting as exemplifying how difficult it is, even in an age

of science, to entirely stamp out firmly established superstitions. Here

are some of the arguments advanced in defence of astrology, taken from

a little brochure entitled "Astrology Vindicated," published in 1898:

"It will be found that a person born when the Sun is in twenty degrees

Scorpio has the left ear as his exceptional feature and the nose

(Sagittarius) bent towards the left ear. A person born when the Sun is

in any of the latter degrees of Taurus, say the twenty-fifth degree,

will have a small, sharp, weak chin, curved up towards Gemini, the two

vertical lines on the upper lip."(4) The time was when science went out

of its way to prove that such statements were untrue; but that time is

past, and such writers are usually classed among those energetic but

misguided persons who are unable to distinguish between logic and

sophistry.

In England, from the time of Elizabeth to the reign of William and Mary,

judicial astrology was at its height. After the great London fire, in

1666, a committee of the House of Commons publicly summoned the famous

astrologer, Lilly, to come before Parliament and report to them on his

alleged prediction of the calamity that had befallen the city. Lilly,

for some reason best known to himself, denied having made such a

prediction, being, as he explained, "more interested in determining

affairs of much more importance to the future welfare of the country."

Some of the explanations of his interpretations will suffice to

show their absurdities, which, however, were by no means regarded as

absurdities at that time, for Lilly was one of the greatest astrologers

of his day. He said that in 1588 a prophecy had been printed in Greek

characters which foretold exactly the troubles of England between the

years 1641. and 1660. "And after him shall come a dreadful dead man,"

ran the prophecy, "and with him a royal G of the best blood in the

world, and he shall have the crown and shall set England on the right

way and put out all heresies." His interpretation of this was that,

"Monkery being extinguished above eighty or ninety years, and the Lord

General's name being Monk, is the dead man. The royal G or C (it is

gamma in the Greek, intending C in the Latin, being the third letter in

the alphabet) is Charles II., who, for his extraction, may be said to be

of the best blood of the world."(5)

This may be taken as a fair sample of Lilly's interpretations of

astrological prophesies, but many of his own writings, while somewhat

more definite and direct, are still left sufficiently vague to allow

his skilful interpretations to set right an apparent mistake. One of

his famous documents was "The Starry Messenger," a little pamphlet

purporting to explain the phenomenon of a "strange apparition of three

suns" that were seen in London on November 19, 1644---the anniversary

of the birth of Charles I., then the reigning monarch. This phenomenon

caused a great stir among the English astrologers, coming, as it did,

at a time of great political disturbance. Prophecies were numerous, and

Lilly's brochure is only one of many that appeared at that time, most of

which, however, have been lost. Lilly, in his preface, says: "If there

be any of so prevaricate a judgment as to think that the apparition of

these three Suns doth intimate no Novelle thing to happen in our own

Climate, where they were manifestly visible, I shall lament their

indisposition, and conceive their brains to be shallow, and voyde of

understanding humanity, or notice of common History."

Having thus forgiven his few doubting readers, who were by no means

in the majority in his day, he takes up in review the records of the

various appearances of three suns as they have occurred during the

Christian era, showing how such phenomena have governed certain human

events in a very definite manner. Some of these are worth recording.

"Anno 66. A comet was seen, and also three Suns: In which yeer, Florus

President of the Jews was by them slain. Paul writes to Timothy. The

Christians are warned by a divine Oracle, and depart out of Jerusalem.

Boadice a British Queen, killeth seventy thousand Romans. The Nazareni,

a scurvie Sect, begun, that boasted much of Revelations and Visions.

About a year after Nero was proclaimed enemy to the State of Rome."

Again, "Anno 1157, in September, there were seen three Suns together, in

as clear weather as could be: And a few days after, in the same month,

three Moons, and, in the Moon that stood in the middle, a white Crosse.

Sueno, King of Denmark, at a great Feast, killeth Canutus: Sueno is

himself slain, in pursuit of Waldemar. The Order of Eremites, according

to the rule of Saint Augustine, begun this year; and in the next, the

Pope submits to the Emperour: (was not this miraculous?) Lombardy was

also adjudged to the Emperour."

Continuing this list of peculiar phenomena he comes down to within a few

years of his own time.

"Anno 1622, three Suns appeared at Heidelberg. The woful Calamities that

have ever since fallen upon the Palatinate, we are all sensible of, and

of the loss of it, for any thing I see, for ever, from the right Heir.

Osman the great Turk is strangled that year; and Spinola besiegeth

Bergen up Zoom, etc."

Fortified by the enumeration of these past events, he then proceeds to

make his deductions. "Only this I must tell thee," he writes, "that

the interpretation I write is, I conceive, grounded upon probable

foundations; and who lives to see a few years over his head, will easily

perceive I have unfolded as much as was fit to discover, and that my

judgment was not a mile and a half from truth."

There is a great significance in this "as much as was fit to

discover"--a mysterious something that Lilly thinks it expedient not to

divulge. But, nevertheless, one would imagine that he was about to

make some definite prediction about Charles I., since these three suns

appeared upon his birthday and surely must portend something concerning

him. But after rambling on through many pages of dissertations upon

planets and prophecies, he finally makes his own indefinite prediction.

"O all you Emperors, Kings, Princes, Rulers and Magistrates of Europe,

this unaccustomed Apparition is like the Handwriting in Daniel to some

of you; it premonisheth you, above all other people, to make your peace

with God in time. You shall every one of you smart, and every one of you

taste (none excepted) the heavie hand of God, who will strengthen your

subjects with invincible courage to suppress your misgovernments and

Oppressions in Church or Common-wealth;... Those words are general: a

word for my own country of England.... Look to yourselves; here's some

monstrous death towards you. But to whom? wilt thou say. Herein we

consider the Signe, Lord thereof, and the House; The Sun signifies in

that Royal Signe, great ones; the House signifies captivity, poison,

Treachery: From which is derived thus much, That some very great man,

what King, Prince, Duke, or the like, I really affirm I perfectly know

not, shall, I say, come to some such untimely end."(6)

Here is shown a typical example of astrological prophecy, which seems to

tell something or nothing, according to the point of view of the reader.

According to a believer in astrology, after the execution of Charles

I., five years later, this could be made to seem a direct and exact

prophecy. For example, he says: "You Kings, Princes, etc.,... it

premonisheth you... to make your peace with God.... Look to yourselves;

here's some monstrous death towards you.... That some very great man,

what King, Prince,. shall, I say, come to such untimely end."

But by the doubter the complete prophecy could be shown to be absolutely

indefinite, and applicable as much to the king of France or Spain as

to Charles I., or to any king in the future, since no definite time is

stated. Furthermore, Lilly distinctly states, "What King, Prince, Duke,

or the like, I really affirm I perfectly know not"--which last, at

least, was a most truthful statement. The same ingenuity that made "Gen.

Monk" the "dreadful dead man," could easily make such a prediction apply

to the execution of Charles I. Such a definite statement that, on such

and such a day a certain number of years in the future, the monarch of

England would be beheaded--such an exact statement can scarcely be found

in any of the works on astrology. It should be borne in mind, also, that

Lilly was of the Cromwell party and opposed to the king.

After the death of Charles I., Lilly admitted that the monarch had

given him a thousand pounds to cast his horoscope. "I advised him," says

Lilly, "to proceed eastwards; he went west, and all the world knows

the result." It is an unfortunate thing for the cause of astrology that

Lilly failed to mention this until after the downfall of the monarch.

In fact, the sudden death, or decline in power, of any monarch, even

to-day, brings out the perennial post-mortem predictions of astrologers.

We see how Lilly, an opponent of the king, made his so-called prophecy

of the disaster of the king and his army. At the same time another

celebrated astrologer and rival of Lilly, George Wharton, also made

some predictions about the outcome of the eventful march from Oxford.

Wharton, unlike Lilly, was a follower of the king's party, but that, of

course, should have had no influence in his "scientific" reading of the

stars. Wharton's predictions are much less verbose than Lilly's, much

more explicit, and, incidentally, much more incorrect in this particular

instance. "The Moon Lady of the 12," he wrote, "and moving betwixt the

8 degree, 34 min., and 21 degree, 26 min. of Aquarius, gives us to

understand that His Majesty shall receive much contentment by certain

Messages brought him from foreign parts; and that he shall receive some

sudden and unexpected supply of... by the means of some that assimilate

the condition of his Enemies: And withal this comfort; that His Majesty

shall be exceeding successful in Besieging Towns, Castles, or Forts, and

in persuing the enemy.

"Mars his Sextile to the Sun, Lord of the Ascendant (which happeneth the

18 day of May) will encourage our Soldiers to advance with much alacrity

and cheerfulness of spirit; to show themselves gallant in the most

dangerous attempt.... And now to sum up all: It is most apparent to

every impartial and ingenuous judgment; That although His Majesty cannot

expect to be secured from every trivial disaster that may befall his

army, either by the too much Presumption, Ignorance, or Negligence of

some particular Persons (which is frequently incident and unavoidable

in the best of Armies), yet the several positions of the Heavens duly

considered and compared among themselves, as well in the prefixed Scheme

as at the Quarterly Ingresses, do generally render His Majesty and his

whole Army unexpectedly victorious and successful in all his designs;

Believe it (London), thy Miseries approach, they are like to be many,

great, and grievous, and not to be diverted, unless thou seasonably

crave Pardon of God for being Nurse to this present Rebellion, and

speedily submit to thy Prince's Mercy; Which shall be the daily Prayer

of Geo. Wharton."(7)

In the light of after events, it is probable that Wharton's stock as

an astrologer was not greatly enhanced by this document, at least among

members of the Royal family. Lilly's book, on the other hand, became a

favorite with the Parliamentary army.

After the downfall and death of Napoleon there were unearthed many

alleged authentic astrological documents foretelling his ruin. And on

the death of George IV., in 1830, there appeared a document (unknown, as

usual, until that time) purporting to foretell the death of the monarch

to the day, and this without the astrologer knowing that his horoscope

was being cast for a monarch. A full account of this prophecy is told,

with full belief, by Roback, a nineteenth-century astrologer. He says:

"In the year 1828, a stranger of noble mien, advanced in life, but

possessing the most bland manners, arrived at the abode of a celebrated

astrologer in London," asking that the learned man foretell his future.

"The astrologer complied with the request of the mysterious visitor,

drew forth his tables, consulted his ephemeris, and cast the horoscope

or celestial map for the hour and the moment of the inquiry, according

to the established rules of his art.

"The elements of his calculation were adverse, and a feeling of gloom

cast a shade of serious thought, if not dejection, over his countenance.

"'You are of high rank,' said the astrologer, as he calculated and

looked on the stranger, 'and of illustrious title.' The stranger made

a graceful inclination of the head in token of acknowledgment of the

complimentary remarks, and the astrologer proceeded with his mission.

"The celestial signs were ominous of calamity to the stranger, who,

probably observing a sudden change in the countenance of the astrologer,

eagerly inquired what evil or good fortune had been assigned him by the

celestial orbs.

"'To the first part of your inquiry,' said the astrologer, 'I can readily

reply. You have been a favorite of fortune; her smiles on you have been

abundant, her frowns but few; you have had, perhaps now possess, wealth

and power; the impossibility of their accomplishment is the only limit

to the fulfilment of your desires.'"

"'You have spoken truly of the past,' said the stranger. 'I have full

faith in your revelations of the future: what say you of my pilgrimage

in this life--is it short or long?'

"'I regret,' replied the astrologer, in answer to this inquiry, 'to be

the herald of ill, though TRUE, fortune; your sojourn on earth will be

short.'

"'How short?' eagerly inquired the excited and anxious stranger.

"'Give me a momentary truce,' said the astrologer; 'I will consult the

horoscope, and may possibly find some mitigating circumstances.'

"Having cast his eyes over the celestial map, and paused for some

moments, he surveyed the countenance of the stranger with great

sympathy, and said, 'I am sorry that I can find no planetary influences

that oppose your destiny--your death will take place in two years.'

"The event justified the astrologic prediction: George IV. died on May

18, 1830, exactly two years from the day on which he had visited the

astrologer."(8)

This makes a very pretty story, but it hardly seems like occult insight

that an astrologer should have been able to predict an early death of a

man nearly seventy years old, or to have guessed that his well-groomed

visitor "had, perhaps now possesses, wealth and power." Here again,

however, the point of view of each individual plays the governing part

in determining the importance of such a document. To the scientist

it proves nothing; to the believer in astrology, everything. The

significant thing is that it appeared shortly AFTER the death of the

monarch.

On the Continent astrologers were even more in favor than in England.

Charlemagne, and some of his immediate successors, to be sure, attempted

to exterminate them, but such rulers as Louis XI. and Catherine de'

Medici patronized and encouraged them, and it was many years after the

time of Copernicus before their influence was entirely stamped out even

in official life. There can be no question that what gave the color

of truth to many of the predictions was the fact that so many of the

prophecies of sudden deaths and great conflagrations were known to have

come true--in many instances were made to come true by the astrologer

himself. And so it happened that when the prediction of a great

conflagration at a certain time culminated in such a conflagration,

many times a second but less-important burning took place, in which

the ambitious astrologer, or his followers, took a central part about

a stake, being convicted of incendiarism, which they had committed in

order that their prophecies might be fulfilled.

But, on the other hand, these predictions were sometimes turned to

account by interested friends to warn certain persons of approaching

dangers.

For example, a certain astrologer foretold the death of Prince Alexander

de' Medici. He not only foretold the death, but described so minutely

the circumstances that would attend it, and gave such a correct

description of the assassin who should murder the prince, that he was

at once suspected of having a hand in the assassination. It developed

later, however, that such was probably not the case; but that some

friend of Prince Alexander, knowing of the plot to take his life, had

induced the astrologer to foretell the event in order that the prince

might have timely warning and so elude the conspirators.

The cause of the decline of astrology was the growing prevalence of the

new spirit of experimental science. Doubtless the most direct blow was

dealt by the Copernican theory. So soon as this was established, the

recognition of the earth's subordinate place in the universe must

have made it difficult for astronomers to be longer deceived by such

coincidences as had sufficed to convince the observers of a more

credulous generation. Tycho Brahe was, perhaps, the last astronomer

of prominence who was a conscientious practiser of the art of the

astrologer.

VII. FROM PARACELSUS TO HARVEY

PARACELSUS

In the year 1526 there appeared a new lecturer on the platform at the

University at Basel--a small, beardless, effeminate-looking person--who

had already inflamed all Christendom with his peculiar philosophy, his

revolutionary methods of treating diseases, and his unparalleled success

in curing them. A man who was to be remembered in after-time by some as

the father of modern chemistry and the founder of modern medicine;

by others as madman, charlatan, impostor; and by still others as a

combination of all these. This soft-cheeked, effeminate, woman-hating

man, whose very sex has been questioned, was Theophrastus von Hohenheim,

better known as Paracelsus (1493-1541).