_Galileo's Birth—Family—Education—Observation of the
Pendulum—Pulsilogies—Hydrostatical Balance—Lecturer at Pisa._
GALILEO GALILEI was born at Pisa, on the 15th day of February, 1564, of
a noble and ancient Florentine family, which, in the middle of the
fourteenth century, adopted this surname instead of Bonajuti, under
which several of their ancestors filled distinguished offices in the
Florentine state. Some misapprehension has occasionally existed, in
consequence of the identity of his proper name with that of his family;
his most correct appellation would perhaps be Galileo de' Galilei, but
the surname usually occurs as we have written it. He is most commonly
spoken of by his Christian name, agreeably to the Italian custom; just
as Sanzio, Buonarotti, Sarpi, Reni, Vecelli, are universally known by
their Christian names of Raphael, Michel Angelo, Fra Paolo, Guido, and
Titian.
Several authors have followed Rossi in styling Galileo illegitimate, but
without having any probable grounds even when they wrote, and the
assertion has since been completely disproved by an inspection of the
registers at Pisa and Florence, in which are preserved the dates of his
birth, and of his mother's marriage, eighteen months previous to it.[4]
His father, Vincenzo Galilei, was a man of considerable talent and
learning, with a competent knowledge of mathematics, and particularly
devoted to the theory and practice of music, on which he published
several esteemed treatises. The only one which it is at present easy to
procure—his Dialogue on ancient and modern music—exhibits proofs, not
only of a thorough acquaintance with his subject, but of a sound and
vigorous understanding applied to other topics incidentally discussed.
There is a passage in the introductory part, which becomes interesting
when considered as affording some traces of the precepts by which
Galileo was in all probability trained to reach his preeminent station
in the intellectual world. "It appears to me," says one of the speakers
in the dialogue, "that they who in proof of any assertion rely simply on
the weight of authority, without adducing any argument in support of it,
act very absurdly: I, on the contrary, wish to be allowed freely to
question and freely to answer you without any sort of adulation, as well
becomes those who are truly in search of truth." Sentiments like these
were of rare occurrence at the close of the sixteenth century, and it is
to be regretted that Vincenzo hardly lived long enough to witness his
idea of a true philosopher splendidly realized in the person of his son.
Vincenzo died at an advanced age, in 1591. His family consisted of three
sons, Galileo, Michel Angelo, and Benedetto, and the same number of
daughters, Giulia, Virginia, and Livia. After Vincenzo's death the chief
support of the family devolved upon Galileo, who seems to have assisted
them to his utmost power. In a letter to his mother, dated 1600,
relative to the intended marriage of his sister Livia with a certain
Pompeo Baldi, he agrees to the match, but recommends its temporary
postponement, as he was at that time exerting himself to furnish money
to his brother Michel Angelo, who had received the offer of an
advantageous settlement in Poland. As the sum advanced to his brother,
which prevented him from promoting his sister's marriage, did not exceed
200 crowns, it may be inferred that the family were in a somewhat
straitened condition. However he promises, as soon as his brother should
repay him, "to take measures for the young lady, since she too is bent
upon _coming out_ to prove the miseries of this world."—As Livia was at
the date of this letter in a convent, the last expression seems to
denote that she had been destined to take the veil. This proposed
marriage never took place, but Livia was afterwards married to Taddeo
Galletti: her sister Virginia married Benedetto Landucci. Galileo
mentions one of his sisters, (without naming her) as living with him in
1619 at Bellosguardo. Michel Angelo is probably the same brother of
Galileo who is mentioned by Liceti as having communicated from Germany
some observations on natural history.[5] He finally settled in the
service of the Elector of Bavaria; in what situation is not known, but
upon his death the Elector granted a pension to his family, who then
took up their abode at Munich. On the taking of that city in 1636, in
the course of the bloody thirty years' war, which was then raging
between the Austrians and Swedes, his widow and four of his children
were killed, and every thing which they possessed was either burnt or
carried away. Galileo sent for his two nephews, Alberto and a younger
brother, to Arcetri near Florence, where he was then living. These two
were then the only survivors of Michel Angelo's family; and many of
Galileo's letters about that date contain allusions to the assistance he
had been affording them. The last trace of Alberto is on his return into
Germany to the Elector, in whose service his father had died. These
details include almost every thing which is known of the rest of
Vincenzo's family.
Galileo exhibited early symptoms of an active and intelligent mind, and
distinguished himself in his childhood by his skill in the construction
of ingenious toys and models of machinery, supplying the deficiencies of
his information from the resources of his own invention; and he
conciliated the universal good-will of his companions by the ready good
nature with which he employed himself in their service and for their
amusement. It is worthy of observation, that the boyhood of his great
follower Newton, whose genius in many respects so closely resembled his
own, was marked by a similar talent. Galileo's father was not opulent,
as has been already stated: he was burdened with a large family, and was
unable to provide expensive instructors for his son; but Galileo's own
energetic industry rapidly supplied the want of better opportunities;
and he acquired, under considerable disadvantages, the ordinary
rudiments of a classical education, and a competent knowledge of the
other branches of literature which were then usually studied. His
leisure hours were applied to music and drawing; for the former
accomplishment he inherited his father's talent, being an excellent
performer on several instruments, especially on the lute; this continued
to be a favourite recreation during the whole of his life. He was also
passionately fond of painting, and at one time he wished to make it his
profession: and his skill and judgment of pictures were highly esteemed
by the most eminent contemporary artists, who did not scruple to own
publicly their deference to young Galileo's criticism.
When he had reached his nineteenth year, his father, becoming daily more
sensible of his superior genius, determined, although at a great
personal sacrifice, to give him the advantages of an university
education. Accordingly, in 1581, he commenced his academical studies in
the university of his native town, Pisa, his father at this time
intending that he should adopt the profession of medicine. In the
matriculation lists at Pisa, he is styled Galileo, the son of Vincenzo
Galilei, a Florentine, Scholar in Arts. His instructor was the
celebrated botanist, Andreas Cæsalpinus, who was professor of medicine
at Pisa from 1567 to 1592. Hist. Acad. Pisan.; Pisis, 1791. It is dated
5th November, 1581. Viviani, his pupil, friend, and panegyrist, declares
that, almost from the first day of his being enrolled on the lists of
the academy, he was noticed for the reluctance with which he listened to
the dogmas of the Aristotelian philosophy, then universally taught; and
he soon became obnoxious to the professors from the boldness with which
he promulgated what they styled his philosophical paradoxes. His early
habits of free inquiry were irreconcileable with the mental quietude of
his instructors, whose philosophic doubts, when they ventured to
entertain any, were speedily lulled by a quotation from Aristotle.
Galileo thought himself capable of giving the world an example of a
sounder and more original mode of thinking; he felt himself destined to
be the founder of a new school of rational and experimental philosophy.
Of this we are now securely enjoying the benefits; and it is difficult
at this time fully to appreciate the obstacles which then presented
themselves to free inquiry: but we shall see, in the course of this
narrative, how arduous their struggle was who happily effected this
important revolution. The vindictive rancour with which the partisans of
the old philosophy never ceased to assail Galileo is of itself a
sufficient proof of the prominent station which he occupied in the
contest.
Galileo's earliest mechanical discovery, to the superficial observer
apparently an unimportant one, occurred during the period of his studies
at Pisa. His attention was one day arrested by the vibrations of a lamp
swinging from the roof of the cathedral, which, whether great or small,
seemed to recur at equal intervals. The instruments then employed for
measuring time were very imperfect: Galileo attempted to bring his
observation to the test before quitting the church, by comparing the
vibrations with the beatings of his own pulse, and his mind being then
principally employed upon his intended profession, it occurred to him,
when he had further satisfied himself of their regularity by repeated
and varied experiments, that the process he at first adopted might be
reversed, and that an instrument on this principle might be usefully
employed in ascertaining the rate of the pulse, and its variation from
day to day. He immediately carried the idea into execution, and it was
for this sole and limited purpose that the first pendulum was
constructed. Viviani tells us, that the value of the invention was
rapidly appreciated by the physicians of the day, and was in common use
in 1654, when he wrote.
[Illustration: Instrument No. 1, No. 2, No. 3]
Santorio, who was professor of medicine at Padua, has given
representations of four different forms of these instruments, which he
calls pulsilogies, (_pulsilogias_,) and strongly recommends to medical
practitioners.[6] These instruments seem to have been used in the
following manner: No. 1 consists merely of a weight fastened to a string
and a graduated scale. The string being gathered up into the hand till
the vibrations of the weight coincided with the beatings of the
patient's pulse, the length was ascertained from the scale, which, of
course, if great, indicated a languid, if shorter, a more lively action.
In No. 2 the improvement is introduced of connecting the scale and
string, the length of the latter is regulated by the turns of a peg at
_a_, and a bead upon the string at _b_ showed the measure. No. 3 is
still more compact, the string being shortened by winding upon an axle
at the back of the dial-plate. The construction of No. 4, which Santorio
claims as his own improvement, is not given, but it is probable that the
principal index, by its motion, shifted a weight to different distances
from the point of suspension, and that the period of vibration was
still more accurately adjusted by a smaller weight connected with the
second index. Venturi seems to have mistaken the third figure for that
of a pendulum clock, as he mentions this as one of the earliest
adaptations of Galileo's principle to that purpose;[7] but it is
obvious, from Santorio's description, that it is nothing more than a
circular scale, the index showing, by the figure to which it points, the
length of string remaining unwound upon the axis. We shall, for the
present, postpone the consideration of the invention of pendulum clocks,
and the examination of the different claims to the honour of their first
construction.
At the time of which we are speaking, Galileo was entirely ignorant of
mathematics, the study of which was then at a low ebb, not only in
Italy, but in every part of Europe. Commandine had recently revived a
taste for the writings of Euclid and Archimedes, and Vieta Tartalea and
others had made considerable progress in algebra, Guido Ubaldi and
Benedetti had done something towards establishing the principles of
statics, which was the only part of mechanics as yet cultivated; but
with these inconsiderable exceptions the application of mathematics to
the phenomena of nature was scarcely thought of. Galileo's first
inducement to acquire a knowledge of geometry arose from his partiality
for drawing and music, and from the wish to understand their principles
and theory. His father, fearful lest he should relax his medical
studies, refused openly to encourage him in this new pursuit; but he
connived at the instruction which his son now began to receive in the
writings of Euclid, from the tuition of an intimate friend, named
Ostilio Ricci, who was one of the professors in the university.
Galileo's whole attention was soon directed to the enjoyment of the new
sensations thus communicated to him, insomuch that Vincenzo, finding his
prognostics verified, began to repent his indirect sanction, and
privately requested Ricci to invent some excuse for discontinuing his
lessons. But it was fortunately too late; the impression was made and
could not be effaced; from that time Hippocrates and Galen lay unheeded
before the young physician, and served only to conceal from his father's
sight the mathematical volumes on which the whole of his time was really
employed. His progress soon revealed the true nature of his pursuits:
Vincenzo yielded to the irresistible predilection of his son's mind, and
no longer attempted to turn him from the speculations to which his whole
existence was thenceforward abandoned.
After mastering the elementary writers, Galileo proceeded to the study
of Archimedes, and, whilst perusing the Hydrostatics of that author,
composed his earliest work,—an Essay on the Hydrostatical Balance. In
this he explains the method probably adopted by Archimedes for the
solution of Hiero's celebrated question[8], and shows himself already
well acquainted with the true principles of specific gravities. This
essay had an immediate and important influence on young Galileo's
fortunes, for it introduced him to the approving notice of Guido Ubaldi,
then one of the most distinguished mathematicians of Italy. At his
suggestion Galileo applied himself to consider the position of the
centre of gravity in solid bodies, a choice of subject that sufficiently
showed the estimate Ubaldi had formed of his talents; for it was a
question on which Commandine had recently written, and which engaged at
that time the attention of geometricians of the highest order. Galileo
tells us himself that he discontinued these researches on meeting with
Lucas Valerio's treatise on the same subject. Ubaldi was so much struck
with the genius displayed in the essay with which Galileo furnished him,
that he introduced him to his brother, the Cardinal Del Monte: by this
latter he was mentioned to Ferdinand de' Medici, the reigning Duke of
Tuscany, as a young man of whom the highest expectations might be
entertained. By the Duke's patronage he was nominated, in 1589, to the
lectureship of mathematics at Pisa, being then in his twenty-sixth year.
His public salary was fixed at the insignificant sum of sixty crowns
annually, but he had an opportunity of greatly adding to his income by
private tuition.
FOOTNOTES:
[4] Erythræus, Pinacotheca, vol. i.; Salusbury's Life of Galileo. Nelli,
Vita di Gal. Galilei.
[5] De his quæ diu vivunt. Patavii, 1612.
[6] Comment, in Avicennam. Venetiis, 1625.
[7] Essai sur les Ouvrages de Leonard da Vinci. Paris, 1797.
[8] See Treatise on HYDROSTATICS.