PHYSICAL SCIENCE OF THE CENTURY
While it is universally conceded that the Renaissance was a supremely
great period in all the arts and literature, in education and
scholarship, and that its geographical discoveries made it noteworthy
from another standpoint, there is a very prevalent impression that it
was distinctly lacking in scientific development and that indeed the
proper attitude of mind for successful scientific investigation was a
much later evolution. Most of the discoveries of even basic notions in
science are almost universally thought to have been reserved for our
time or at least for generations much nearer to us than Columbus'
Century.
Nothing could well be less consonant with the actual history of
science than any such impression. At many times before ours man has
made great scientific progress. The greatest mystery of human history
is that often after great discoveries were made they were somehow lost
sight of. Over and over again men forget their previous knowledge and
have to begin once more. There was one of these magnificent
developments of scientific thought in every department during
Columbus' Century and discoveries were made and conclusions reached
which revolutionized other modes of scientific thinking just as much
as Columbus' discovery of America revolutionized geography, or the
work of Raphael or Michelangelo and Leonardo revolutionized the
artistic thought of the world.
When we recall that it was at this time that Copernicus set forth the
theory which has probably more influenced human thinking than any
other and that this discovery developed directly from the mathematics
of the time and while Vesalius revolutionized anatomy, the discovery
of the circulation of the blood began a similar revolution in
physiology and the foundations of botany and of modern chemistry in
their relations to medicine were laid, some idea of the greatness of
the {344} scientific advance of this period will be realized.
Mathematics, particularly, developed marvellously and it is always
when new horizons are opening out in mathematics that the exact
sciences are sure to have a period of wonderful progress. Beautiful
hospitals were erected and whenever there are good hospitals, surgery
makes progress and that care for the patient which constitutes the
essential part of medicine at all times, receives careful attention.
Above all the men of the Renaissance took it on themselves to edit and
translate and publish the ancient classics of science and make them
available for the study of their own and subsequent generations. The
debt which the modern world owes to the Renaissance in this matter is
only coming to be properly realized as a consequence of our own
development of scholarship in this generation. Only the profound
scholar is likely to appreciate properly how much we are indebted to
the patient, time-taking work of this period in making books
available. Not only the ancient classics but also the works of the
Middle Ages on scientific subjects were all published. The early
Christian scholars, the Arabians, and above all, the great teachers of
the later Middle Ages were edited and printed as an enduring heritage
for mankind.
The index of the feeling of the time toward physical science as well
as the interest of the scholars of the period in nearly every phase of
it is illustrated by the life of Cardinal Nicholas of Cusa, who is
usually known as Cusanus. He was a distinguished German churchman who
was made Bishop of Brixen and afterwards Cardinal and who had the
confidence of the Popes to such a degree that he was sent out as
Legate for the correction of abuses in Germany. He was particularly
interested in mathematics and the great German historian of
mathematics. Cantor, devotes a score of pages to the advances in
mathematics which we owe to Cusanus. According to tradition during his
journeys over the rough roads in the rude carriage of the time, he
studied the curve described through the air by a fly as it was carried
round the wheel after alighting on the top of it. He recognized this
as a particular kind of curve which we know now as the cycloid and he
studied many of its peculiarities and suggested its mathematical
import.
{345}
He was particularly interested in astronomy and declared that the
earth was round, was not the centre of the universe and that it could
not be absolutely at rest. As he put it in Latin: _terra igitur, quae
centrum esse nequit, motu omni carere non potest._ He described very
clearly how the earth moved around its own axis, and then he added
what cannot but seem a surprising declaration for those who in our
time think such an idea of much later origin, that he considered that
the earth itself cannot be fixed, but moves as do the other stars in
the heavens, _Consideravi quod terra ista non potest esse fixa sed
movetur ut aliae stellae._ More surprising still, he even seems to
have reached by anticipation some idea of the constitution of the sun.
He said: "To a spectator on the surface of the sun the splendor which
appears to us would be invisible since it contains as it were an earth
for its central mass with a circumferential envelope of light and heat
and between the two an atmosphere of water and clouds and of ambient
air."
These expressions occur mainly in a book _"De Docta Ignorantia,"_ in
which the Cardinal points out how many things which even educated
people think they know are quite wrong. His other books are on
mathematics, though there is a little treatise on the correction of
the calendar which shows how thoroughly the men of the time recognized
the error that had crept into the year and how capable they were of
making the correction. In a book of his on "Static Experiments" he has
a very original discussion of laboratory methods for the study of
disease which is eminently scientific, and which is described in the
chapter on Medicine.
The life of George von Peuerbach, also Puerbach and Purbachius, the
Austrian astronomer, one of Cardinal Nicholas' proteges who lived to
be scarcely forty and whose greatest work was done just at the
beginning of Columbus' Century, is an excellent index of the
scientific spirit of the time. About 1440, when he was not yet twenty
years of age, he received the degree of Master of Philosophy and of
the Liberal Arts with the highest honors at the University of Vienna.
After this he seemed to have spent some time at postgraduate work in
Vienna, especially in mathematics under Johann von Gmuenden. Just about
the beginning of Columbus' Century he went to {346} Italy. Cardinal
Nicholas of Cusa became interested in him and secured him a
lectureship on Astronomy at the University of Ferrara. During the next
few years he refused offers of professorships, at Bologna and Padua,
because he wanted to go back to Vienna to teach in his alma mater.
There, with the true Renaissance spirit of non-specialism, he lectured
on philology and classical literature, giving special postgraduate
courses in mathematics and astronomy. It was at this time that Johann
Mueller, Regiomontanus, as he is known, came under his tutelage.
Purbach deserves the name that has been given him of the father of
mathematical astronomy in modern times.
He introduced the decimal system to replace the cumbersome duodecimal
method of calculation, which up to his time had been used in
mathematical astronomy. He took up the translation of Ptolemy's
"Almagest," replaced chords by sines and calculated tables of sines
for every minute of arc for a radius of 600,000 units. This wonderful
work of simplification naturally attracted wide attention. Cardinal
Bessarion was brought in touch with him during a visit to Vienna and
was impressed with his genius as an observer and a teacher. He
suggested that the work on Ptolemy should not be done on the faulty
Latin translation which was the only one available in Vienna at the
moment, but on some of the Greek manuscripts of the great Alexandrian
astronomer. He offered to secure them and also to provide for
Purbach's support during the stay in Rome necessary for the study. The
invitation was accepted on condition that his pupil Regiomontanus
should go with him. Unfortunately, however, Purbach died before his
journey to Rome. His works were very popular in his own time and his
commentary on the "Almagest of Ptolemy" as completed by Regiomontanus
became one of the standard text-books of the time. Altogether there
are some twenty of his works extant and his "New Theory of the
Planets" remained a favorite book of reference for astronomers even
long after the publication of Copernicus. His industry must have been
enormous but was after all not different from that of many of his
contemporaries.
Astronomy was to be the great stimulating physical science of the
early part of Columbus' Century and Purbach's successor {347} in the
chain of scientific genius at this time was his pupil Johann Mueller,
or as he has come to be known from the Latinization of the name of the
place of his birth, Koenigsberg (in Franconia, not far from Munich),
Regiomontanus. As we have said, young Mueller made his studies with
Purbach at Vienna, became very much interested in astronomy and
mathematics, at his master's suggestion accompanied Cardinal Bessarion
to Italy and under his patronage took up the work of providing an
abridgment of Ptolemy's great work, the "Almagest," in a Latin
translation for those who might be deterred from the Greek.
Cardinal Bessarion became very much interested in him and gave him a
chance to study in Italy. Mueller chose Padua and spent nearly ten
years there. Whenever anybody in almost any country in Europe wanted
to secure opportunities for study beyond those afforded by his native
land at this time he went down to Padua. Linacre, Vesalius, John Caius
went there for medicine, Copernicus, a little later than
Regiomontanus, for mathematics and astronomy and it was the ardently
desired goal of many a student's wishes. Mueller spent nearly ten years
in Italy, most of it at Padua and at the age of about thirty-five
returned to Germany to take up his life work. He settled down in
Nuremberg, where in connection with Bernard Walther he secured the
erection of an observatory. Nuremberg, because of its fine work in the
metals, was the best place to obtain mechanical contrivances of all
kinds, and many of these were used for the first time for scientific
purposes at this observatory. It became quite a show place for
visitors and while Nuremberg was developing the literary and artistic
circles in which the Pirkheimers, Albrecht Duerer and the Vischers and
Adam Kraft shone conspicuously, scientific interest in the city was at
a similar high level.
Mueller made a series of observations of great value in the astronomy
of the time and substituted Venus for the moon as a connecting link
between observations of the sun, the stars and the earth. He
recognized the influence of refraction in altering the apparent places
of the stars and he introduced the use of the tangent in mathematics.
His most important work for the time, however, was the publication of
a series of astronomical {348} leaflets, _"Ephemerides Astronomicae"_
in which his observations were published and also a series of
calendars for popular information. These announced the eclipses, solar
and lunar, for years before their recurrence and gave a high standing
to astronomy as a science. Some of these leaflets even reached Spain
and Portugal and encouraged Spanish and Portuguese navigators with the
thought that they could depend on observations of the stars for their
guidance at sea. In a way, then, Regiomontanus' work prepared the path
along which Columbus' discovery was made.
Regiomontanus' work attracted so much attention that he was invited to
Rome to become the Papal Astronomer and to take up the practical work
of correcting the Calendar. Unfortunately he died not long after his
arrival in Rome, though not before he had been chosen as Bishop of
Regensberg (Ratisbon) as a tribute to his scholarship and his piety.
He thus became a successor of Albertus Magnus (in the bishopric), who
had been in his time one of the profoundest of scholars and greatest
of scientists. The tradition of appreciation of scholarship and
original research had evidently been maintained for the three
centuries that separate the two bishop scientists.
A distinguished scientific student born at Nuremberg the same year as
Regiomontanus was Martin Behem or Behaim, the well-known navigator and
cartographer, who on his return to Nuremberg in 1493 made the famous
terrestrial globe which was meant to illustrate for his townsmen the
present state of geography as the Spaniards and Portuguese had been
remaking it. Behem's work is a striking testimony to the excellence of
geographic knowledge at this time, and only for the preservation of
this globe we could scarcely have believed in the modern time how
correct were the notions of the scholars of the period with regard to
the older continent at least.
One of the great physical scientists of this time is Toscanelli, the
physician, mathematician, astronomer and cosmographer, over whose
connection with Columbus such a controversy has raged in recent years.
He and Cardinal Cusanus were fellow students at the University of
Padua, where Toscanelli's course consisted of mathematics, philosophy
and medicine. He settled down as a practising physician in Florence
and took up {349} scientific studies of many kinds which brought him
into connection not only with the students of science, but with the
scholars and artists of the time. Brunelleschi and he were intimate
friends, but he was well known outside of Italy, and Regiomontanus
often consulted him. His services to astronomy consist in the
painstaking and exact observations on the orbit of the comets of 1433,
1449-50 and especially of Halley's comet on its appearance in 1456 and
of the comets of May, 1457, June, July and August of the same year.
These show a most accurate power of astronomical observation and
profound mathematical knowledge for that time. His famous chart
indicated just how a navigator might reach the coast of India by
sailing westward, and Columbus is said to have carried a copy of this
chart with him on his first voyage. Whether this is true or not, there
is no doubt of Toscanelli's place in the history of science because of
original work in astronomy, geodesy and geography.
The most important protagonist of physical science during Columbus'
Century, however, was undoubtedly Copernicus. Columbus gave the men of
his time a new world, but Copernicus gave them a new creation. When
early in the sixteenth century he published a preliminary sketch of
his theory, one of his ecclesiastical friends remarked to him that he
was giving his generation a new universe. There has probably never
been a theory advanced which has changed men's modes of thinking with
regard to the world they live in and their relation to it as the
Copernican hypothesis has done, though it must not be forgotten that
there are some as yet insuperable difficulties which keep it still in
the class of scientific hypotheses.
The earth had up to this time been universally thought of as the
centre of the universe, much more important than any of the other
bodies, sun, moon or stars, and all the others were thought to move
around it. Their apparent movement was due to the rotation of the
earth, which was quite unrecognized. The immense distances of space
were entirely undreamt of. In the new order of thinking the earth
became a minor planet of small size in our solar system which was of
inconspicuous magnitude when compared to the totality of the other
bodies of the universe. The acceptance of the new theory sank man in
his own estimation very considerably. The change of point of view of
{350} the meaning of the universe necessitated by the Copernican
theory was ever so much greater than that demanded by evolution in our
time.
It took two centuries for men to adjust their thinking to these new
ideas. Francis Bacon, a full century after Copernicus' time, declared
emphatically that the Copernican theory did not explain the known
facts of astronomy as well as the Ptolemaic theory. In Bacon's time
Galileo was the subject of persecution and the reason for the
persecution was that he was advancing a doctrine which no other great
astronomer of his time accepted, and advancing it for reasons which
have not held in the after-time. The Copernican theory came eventually
to be accepted for quite different reasons from those advanced by
Galileo.
How Copernicus succeeded in coming to this magnificent generalization
is indeed hard to understand. It is easier to get some notion of it,
however, when his achievement is taken in connection with what was
being done all around him at this time. Living in a century when great
men were accomplishing triumphs in painting, sculpture, architecture
that have been the wonder of the world ever since, and when geography
was being revolutionized, and nearly every science awakened, it is not
surprising that he should have reached a height of mathematical and
astronomical expression beyond any that men had ever conceived before
and that he should have surpassed many of the generations to come
after him, by the clearness of his intuition of the astronomical
mystery of the universe.
Copernicus had not made many observations nor were such observations
as had been made by him worked out with that painstaking accuracy
which might be thought necessary to reach a great new conception of
the universe. He had the genius to see from even the few and imperfect
data that he had at hand what the true explanation of the diverse
phenomena of the heavens was. He had no demonstrations to advance. He
argued merely from analogy. Even Galileo, a century later, admitted to
Cardinal Bellarmine that he had no strict demonstration of his views
to offer, but that "the system seems to be true." While the feeling of
many scientists in the modern time is that great discoveries come from
patient {351} accumulation of accurate observations in large numbers,
the history of science shows that almost invariably the epochal steps
in progress have come from men who were comparatively young as a rule
and who were not overloaded with the information of their time. The
great artists of the Renaissance could probably have given no better
reasons for their artistic conceptions than Copernicus for his stroke
of genius, but they were all working at a time when somehow men were
capable as they never have been since of these far-reaching
intellectual achievements.
Copernicus was a Pole who, like other students of his time, gladly
welcomed the opportunity to go down to Italy for post-graduate work,
studied with Novara at Padua mathematics and astronomy and was quite
willing to add the study of medicine, because by so doing he could
secure an extension of the length of time he would be allowed to
remain in Italy. He then returned to be a canon of the Cathedral of
Frauenberg, and spent forty years in quiet patient observation and in
the practice of his medical profession not for money, but for the
benefit of the poor and such friends of the chapter of the Cathedral
as he was under obligations to because of the years they had supported
him in Italy. He probably reached his great astronomical theory when
he was about thirty. He did not publish the preliminary sketch of it
for twenty-five years. He did not publish his great book until just
before his death, keeping it by him, making changes in it and while
thoroughly convinced of its importance, quite sure that, owing to its
lack of definite demonstration, it would not be generally accepted.
Like so many of these geniuses of the Renaissance he was a simple
kindly man who had many good friends among those around him and who
had one of the very happy lives accorded to those who, having some
great thought and great work to occupy themselves with, have daily
duties that afford them diversion and bring them into contact with
friends in many ordinary relations in life. His humility of heart and
simplicity of character, as well as his deep religious faith, can be
very well appreciated from the prayer which at his own request was the
only inscription upon his tombstone: "I ask not the {352} grace
accorded to Paul, not that given to Peter; give me only the favor Thou
didst show to the thief on the Cross."
His attitude toward the reform movement, twenty years of which he
lived through in Germany, is interesting. He was an intimate friend of
Bishop Maurice Ferber of Ermland, who kept his see loyal to Rome at an
epoch when the secularization of the Teutonic Order and the falling
away of many bishops all around him make his position and that of his
diocese noteworthy in the history of that place and time. Copernicus
continued loyal to the old Church and in 1541 his great book _"De
Revolutionibus Orbium Celestium"_ was dedicated to Pope Paul III, who
accepted the dedication and until the Galileo matter brought
Copemicanism prominently into question there was never any thought of
Copernicus' book as containing matters opposed to faith. It was then
placed on the _Index_, but only until some minor passages should be
corrected which set forth the new theory as if it were an astronomical
doctrine founded on facts and demonstrations and not a hypothesis
still to be discussed by scientists.
The scientific spirit of this century is often scouted because in
spite of their scientific knowledge many of the astronomers and
mathematicians of this time as well as, of course, other educated men
following their example, could not quite rid themselves of the idea
that the stars were powerful influences over man's life and health.
The history of this idea, however, minimizes the objection. All down
the centuries men like Roger Bacon, Albertus Magnus, Nicholas of Cusa,
Marsilio Ficino and Pico della Mirandola insisted that there could be
nothing in what we now call astrology. Men parted with the older ideas
very slowly, however. Almost a hundred years after Columbus' Century
even Galileo made horoscopes and seems to have thoroughly believed in
them, though some of his prophecies were sadly mistaken. Kepler drew
up horoscopes, confessing that he had not much confidence in them but
that they were paid for much better than other mathematical work and
he sadly needed the money. Lord Bacon could not quite persuade himself
that there was nothing in astrology. As late as after the middle of
the eighteenth century Mesmer's thesis for graduation in medicine at
the University of Vienna, which {353} at that time had one of the best
medical schools of Europe, was on the influence of the stars on human
constitutions. It was accepted by the faculty and he got his degree.
Even in our time, though now the educated contemn, the mass of the
people still have not entirely rejected astrology. The men of
Columbus' Century can scarcely be thought less of for having accepted
it, though many of the scientists of the time did not.
The counterpart to the great scientific genius that Copernicus was,
the generalizer who discloses a new horizon, was to be found in his
contemporary, Leonardo da Vinci, who was an inventor, a practical
genius applying discoveries to everyday life. He solved most of the
mechanical problems, invented locks for canals, the wheelbarrow and
special methods of excavation, a machine for making files by
machinery, run by a weight, a machine for sawing marble blocks instead
of separating them by natural cleavage, the model of those still
employed at Carrara, as well as machines for planing iron, for making
vices, saws and planes, for spinning, for shearing the nap of cloth,
as well as an artist's sketching stool, a color grinder, a spring to
keep doors shut, a roasting jack, a hood for chimneys, movable
derricks quite similar to those in use among us to-day, with
contrivances for setting up marble columns on their bases, one of
which in principle was used to set up Cleopatra's Needle on the
Embankment in London in our time. A favorite field of invention was
that of all sorts of apparatus relating to war, military engines,
devices for pushing scaling ladders away from walls and many others.
He was probably the greatest inventive genius in the world's history.
He had an eminently practical mind. He devoted himself to the problem
of flying, studied the wings of birds and produced a series of
mechanical devices, tending toward the solution of that problem.
Taine said of him: "Leonardo da Vinci is the inventor by anticipation
of all the modern ideas and of all the modern curiosities, a universal
and refined genius, a solitary and inappeasable investigator, pushing
his divinations beyond his century so as at some times to reach ours."
There was scarcely anything that he touched that he did not illuminate
wonderfully by his genius. In studying the muscles of animals he
invented a {354} dynamometer, he improved spectacles and studied the
laws of light, invented the camera obscura and in his steam
experiments anticipated Watt. A very curious feature of his work is
his series of experiments with the steam gun, with which he was sure
that great destruction might be worked.
A very interesting invention of a scientific instrument of some
precision by Leonardo was what may be called a weather gauge. This was
made of a copper ring with a small rod of wood, which acted as a
balance. On it were two little balls, one covered with wax and the
other with material that absorbed moisture readily. When the air was
saturated with moisture this ball grew heavy and inclined the beam
till it touched one of the divisions marked on the copper ring set
behind it. The degree of moisture could thus be seen and the weather,
or at least changes in it, could be predicted. We have a whole series
of such arrangements mainly in the shape of toys in the modern time.
The hygroscopic qualities of cord or the tendency of certain colors to
change their tints when more moisture is present are used to indicate
approaching changes in the weather. Leonardo seems to have been the
first to make use of this practically and he deserves the credit of
priority in the invention.
His studies in optics might almost naturally be expected from a
painter so much occupied with color and whose intense curiosity
prompted him to know not merely the use of things but the causes of
and the reasons for them. He evolved much of the science of color
vision, suggested the principles of optics that came to be known only
much later, analyzed and explained the construction of the eye,
invented the camera obscura in imitation of it and gave us a theory of
color vision which is as good as any other that we have down to the
present day. These optical studies alone might well be considered as
enough to occupy an ordinary lifetime, but they seem to have been only
the results of a series of interludes of the nature of recreation for
Leonardo. He made his notes on the subject, filed them away with
others, made no attempt to print his conclusions, probably found very
few with whom he could discuss the subject, but he had satisfied
himself. That was what he wanted.
{355}
After knowing such facts as this we are not surprised to learn of his
anticipating by some sort of divination the laws of gravitation, the
molecular composition of water, the motion of waves, the undulatory
theory of light and heat, the earth's rotation and rotundity before
Columbus' time and many other surprising things. One finds in his
diary that he was planning the construction of a harbor and studying
the music of the waves on the beach at the same time.
Poggendorff, in his great Biographical Dictionary of prominent men of
science, quotes Libri's "History of Mathematics in Italy" as authority
for the declaration that Leonardo discovered capillarity and
diffraction, made use of the signs + and -, knew the camera obscura
(without a lens), made observations on resistance, on density, on the
weight of the air, on dust figures, on vibrating surfaces and on
friction and its effects.
All sorts of machines came from Leonardo's hands. He had a positive
genius for practical invention that has probably never been equalled,
surely not surpassed, even down to our own day. His inventive faculty
worked itself out, in machines of such variety as have never come from
the brain of a single individual before. Nor were these merely
primitive mechanical devices that we would surely despise now. On the
contrary, nearly all of them have endured in principle at least and
some of them almost as they came from him.
Leonardo also did distinguished work in the biological sciences, so
that Duval, Professor of Anatomy at the University of Paris and
himself well known both for his researches in biology and his
knowledge of the history of science, entitles an article with regard
to him in the French _Revue Scientifique_ (Dec. 7, 1889), "A Biologist
of the Fifteenth Century." His biological discoveries are discussed in
the chapter on the Biological Sciences.
Sometimes it is asserted by those who are so little familiar with the
history of science that they venture on such assertions rather easily,
that the true scientific spirit had not yet awakened and that while
men were making many observations and acquiring new information they
had not as yet the proper scientific attitude of mind to make really
great discoveries. It is {356} rather amusing to be told that of a
century when Copernicus and Vesalius and so many other distinguished
modern scientists were alive. Some writers suggest that the true
rising of the modern spirit of scientific inquiry did not come until
Francis Bacon's time. Francis Bacon is one of the idols of the
marketplace, but surely no serious student of history accords him the
place in science that our English forbears gave him when they were
insular enough to know very little about continental work, and above
all about Italian workers.
Francis Bacon, of course, had been long anticipated in all that
concerns the inductive method in science by his much greater namesake
Roger Bacon. In Columbus' Century however, a hundred years before
Bacon's time, Bernardino Telesio, the Italian philosopher, stated
fully the inductive method and recognized all its possibilities. In
_Science_ for December 19, 1913, Professor Carmichael said of him:
"He abandoned completely the purely intellectual sphere of the
ancient Greeks and other thinkers prior to his time and proposed an
inquiry into the data given by the senses. He held that from these
data all true knowledge really comes. The work of Telesio,
therefore, marks the fundamental revolution in scientific thought by
which we pass over from the ancient to the modern methods. He was
successful in showing that from Aristotle the appeal lay to nature,
and he made possible the day when men would no longer treat the
_ipse dixit_ of the Stagirite philosopher as the final authority in
matters of science."
The tendency of this century to make scientific principles of value
for practical purposes is well illustrated by the references to the
sympathetic telegraph which began to be much talked of at this time.
According to the story as told, friends at a distance might be able to
communicate with each other by having two dials around which the
letters of the alphabet were arranged with a magnetic needle swinging
free as the indicator. When the needle on one of the dials was moved
to a letter, the other by magnetic attraction was supposed to turn to
the same letter. This ingenious conceit has been attributed to
Cardinal Bembo, one of the great scholars of the Renaissance, who was
private secretary to Pope Leo X. His friend {357} Porta, the versatile
philosopher, made it widely known by the vivid description which he
gave of it in his celebrated work on "Natural Magic," published just
after the close of Columbus' Century.
A very important development in science came in the application of
chemistry to medicine, both as regards physiology and pathology. Basil
Valentine at the beginning of Columbus' Century led the way and
Paracelsus did much to indicate what the advantage of the application
of chemistry to medicine would be. Paracelsus compared the processes
in the human body with chemical phenomena and declared that
alterations in the chemical conditions of organs were the causes of
disease. He set himself up in opposition to the humoral theory of the
ancients and denied that the heart was the seat of heat manufacture in
the body, for every portion of the system had, he asserted, its source
of heat. It was through Paracelsus that chemistry was added to the
medical curriculum and George Korn in his chapter on Medical Chemistry
in Puschmann's "Handbook" attributes the foundation of certain
professorships for chemistry at the universities of this time to
Paracelsus' influence. Andreas Libavius did much to advance chemical
science in various directions by his study and preparation of
sulphuric acid and his recognition of the identity of the substance
made from sulphur and saltpeter with that obtained from vitriol and
alum. Studies of this kind brought a broad realization of the
possibilities of chemistry.
The spirit of the period as regards science and the development of the
faculty of observation at this time is very well illustrated by
Columbus' own observations on the declination of the magnetic needle
during his first voyage across the ocean. Brother Potamian has told
the story in "Makers of Electricity" (Fordham University Press, New
York, 1909), page 22:
"It is one of the gems in the crown of Columbus, that he observed,
measured and recorded this strange behavior of the magnetic needle
in his narrative of the voyage. True, he did not notice it until he
was far out on the trackless ocean. A week had elapsed since he left
the lordly Teneriffe, and a few days since the mountainous outline
of Gomera had disappeared {358} from sight. The memorable night was
that of September 13th, 1492. There was no mistaking it; the needle
of the Santa Maria pointed a little west of north instead of due
north. Some days later on September 17th, the pilots, having taken
the sun's amplitude, reported that the variation had reached a whole
point of the compass, the alarming amount of 11 degrees.
"The surprise and anxiety which Columbus manifested on those
occasions may be taken as indications that the phenomenon was new to
him. As a matter of fact, however, his needles were not true even at
the outset of the voyage from the port of Palos, where, though no
one was aware of it, they pointed about 3 deg. east of north. This angle
diminished from day to day as the Admiral kept the prow of his
caravel directed to the West, until it vanished altogether, after
which the needles veered to the West, and kept moving westward for a
time as the flagship proceeded on her voyage.
"Columbus thus determined a place on the Atlantic in which the
magnetic meridian coincided with the geographical and in which the
needle stood true to the pole. Six years later, in 1498, Sebastian
Cabot found another place on the same ocean, a little further north,
in which the compass lay exactly in the north-and-south line. These
two observations, one by Columbus and the other by Cabot, sufficed
to determine the position of the agonic line, or line of no
variation, for that locality and epoch.
"The _Columbian_ line acquired at once considerable importance in
the geographical and the political world, because of the proposal
that was made to discard the Island of Ferro and take it for the
prime meridian from which longitude would be reckoned east and west,
and also because it was selected by Pope Alexander VI to serve as a
line of reference in settling the rival claims of the kingdoms of
Portugal and Castile with regard to their respective discoveries. It
was decided that all recently discovered lands lying to the east of
that line should belong to Portugal; and those of the west to
Castile."
The first observation of magnetic declination on land appears to have
been made about the year 1510 by {359} George Hartmann, Vicar of the
Church of St. Sebald, Nuremberg, who found it to be 6 deg. East in Rome,
where he was living at the time. He observed it also in Nuremberg,
where the needle pointed ten degrees East of North. Columbus'
explanation of the declination to his sailors is interesting. He kept
silence about it at first, but when they grew alarmed, believing that
the laws of nature were changing as they advanced farther and farther
into the unknown, he told them that the needle did not point to the
North Star, which had been called the Cynosure, but to a fixed point
in the celestial sphere and that Polaris itself was not stationary,
but had a rotational movement of its own, like all other heavenly
bodies. They trusted him and their fears were allayed and a mutiny
averted. When on his return to Spain he reported the many and definite
observations on the variation of the compass which he had made he was
told by the scientists of the time that he, and not the needle, was in
error, because the latter was everywhere true to the pole. Just why
they were sure it was so they could not tell, but they refused to
believe even observations which showed that it was not so; though
these were reported by a man who had just overturned quite as strong
convictions by sailing westward and reaching land. It is such
contradictions of what seem to be obviously first principles of
science that in all ages have constituted great discoveries and
required genius to make them.
{360}