BOSCOVICH
692
BOSCOVICH
survey in B-iZil. He volunturily offered his services
for the arduous task, hoping thus to be able to carry
out an independent sur\'ey in Ecuador, and so obtain
data of value for the final solution of the problem of
the figiu-o of the earth, which was then exciting much
attention in England and France. His proposal led
to the institution of similar surveys in the Papal
States, the pope taking tliis means of retaining him
in his own domain. A detailed account of the results
of the work appeared in a large quarto volume
(Rome, 1755) entitled: " De litteraria expeditione per
Pontificiam ditionem ad dinietiendos duos meridiani
gradus et corrigen lam mappam geographicam ". A
map of the Papal States made at the same time,
which corrected many previous errors, proved to be
likewise a welcome contribution to the discussion re-
garding the more or less spherical form of the earth.
Many of the triaugulations were accompanied by no
slight difficulties. The two base-lines employed in
the survey — one on the ^'ia Appia, the other in the
neighbourhood of Rimini — were measured with great
care. The first was redetermined in 1854-55 by
Father Secclii, as the mark indicating one end of the
line measui'etl by Boscovich and Le Maire hatl been lost.
(Cf. Secclii 's work: Misura ilella Base trigonometrica
esequita suUa via Appia per ortline del governo
pontificio, Roma, 1S5S.) Besides his work in mathe-
matical astrono:uy we also find Boscovich speculat-
ing, upon scirniilic L;rounds, on the essence of matter
and endea\durii< in isiablish more widely Newton's
law of miiwrsLiI iiravitation. As early as 174S we
meet essays from his pen in this field of thought, e. g.
"De materiiE divisibilitate et de principiis corporum
dissertatio" (1748); "De continuitatis lege et ejus
consectariis pertinentibus ad prima materia? elementa
eormnque vires" (1754); "De lege virium in natura
existentium" (1755); " Philosophiie naturalis theoria
redacta ad unicam legem virium in natura existen-
tium" (1758). Boscovich, according to the views
expressed in these essays, held that bodies could not
be composed of a continuous material substance,
nor even of contigvious material particles, but of in-
numerable, point-like structures whose individual
components lack all extension and divisibility. A
repulsion exists between them which is indeed in-
finitesimal but cannot vanish without compenetration
taking place. This repulsion is due to certain forces
with which these elements are endowed. It tends to
become infinite when they are in very close proximitj',
whereas w-ithin certain limits it diminishes as the
distance is increased and finally becomes an at-
tractive force. This change is brought about by the
diverse directions of the various forces. Boscovich
divided his last-mentioned exhaustive work into
tlu-ee parts, first explaining and establishing his
theory, then pointing out its applications to me-
chanical problems, and finally showing how it may
be employed in physics. His attempt to reduce the
most complicated laws of nature to a simple funda-
mental law aroused so much interest that in 1763 a
third, and enlarged, edition of his "Theoria philo-
sophise naturalis" (Venice, 1763) had become neces-
sary. The publisher added as an appendix a cata-
logue of Boscovich 's previous works. There are no
less than sixty-six treatises dating from 1736 — a
Croof of his literary activity. Some have already een mentioned and to these may be added his "Elementorum matheseos tomi tres", in quarto (1752).
Boscovich attracted attention by his political ■nTitings as 'well as by his scientific achievements. His Latin verses in which he eulogized the Polish king, Stanislaus, Pope Benedict XIV', and various Venetian noblemen, were read before the Arcadian Academy of Rome. His "Carmen de Soils ac Lunse defectibus" (o vols., London, 1760) was much ad- mired. His services were also in demand in several
cities and provinces. Thus, in 1757, he was sent by
the city of Lucca to the Court of Vienna, to urge the
damming of the lakes which were tlireatening the
city. He acquitted himself of this task with such
skill that the Luccans made him an honorary citizen
and rendered him generous assistance on his scientific
journeys, both in Italy, France, and England. AVhile
in England he gave the impulse to the observations
of the approaching transit of Venus, on 6 June, 1761,
and it is not unlikely that his proposal to employ
lenses composed of liquids, to avoid chromatic
aberration, may have contributed to DoUond's suc-
cess in constructing acliromatic telescopes. The
citizens of Ragusa, his native town, besought him to
settle a dispute in which they had become involved
\\'ith the King of France — an affair which the pope
liimself deignetl to adjust. Boscovich returned from
England in company with the Venetian ambassador
who took him by way of Poland as far as Constanti-
nople. He availed himself of this opportunity to
extend and complete his archaeological studies in
these countries, as may be gathered from liis journal
published at Bassano in 1784: "Giornale d'un viaggio
da Constantinopoli in Polonia con ima relazione delle
rovine cU Troja". The hardships of this journey
shattered his health, yet we find him shortly after
(1762) employed at Rome in various practical works,
such as the draining of the Pontine marshes. In
1764 he accepted the appointment of professor of
mathematics at the L'niversity of Pavia (Ticinum).
At the same time Father La Grange, the former assist-
ant of Father Pezenas of the Observatory of Marseilles,
was invited by the Jesuits of Milan to erect an ob-
servatory at the large college of Brera. He was able
to avail liimself of the technical skill of Boscovich in
carrj-ing out his commission and it may be ques-
tioned to which of the two belongs the greater credit
in the foimding of this observatory which, even in
our own time, with that of the Collegio Romano, is
among the most prominent of Italy. It was Bosco-
^^ch who selected the south-east corner of the college
as a site for the observatory and worked out the com-
plete plans, including the reinforcements and the
necessary remodelling for the structure. Building
operations were immei-liately begun and in the fol-
lowing year, 1765, a large room for the mural quad-
rants and meridian instnmients, another for the
smaller instruments, and a broad terrace, with several
revolving domes to contain the sextants and equa-
torials, were completed. Such was the stability of
the observatory that the new 18-inch glass of Scliiapa-
relli could be mounted in it although a cylindrical
dome with a diameter of 13 yards, 4 inches now
takes the place of the octagonal hall of Boscovich.
The London Academy proposed to send Boscovich
in charge of a scientific expedition to California to
observe the transit of Venus in 1769 but, unfortu-
nately, the opposition manifested everjT\'liere to the
Society of Jesus and leading finally to its suppression,
made this impossible. He continued, however, to
give his services to the Milan Observatory for wliose
further development he was able to obtain no in-
considerable sums of money. In particular the ad-
justment of the instrmncnts engaged his attention,
a subject about which he has left several papers.
But as his elaborate plans received only partial sup-
port from his superiors and patrons, he thought
seriously in 1772 of severing his connexion with the
observatory and, in fact, in the same year. Father
La Grange was placed in complete charge of the new
institution. Boscovich was to become professor at
the University of Pisa, but Louis XV gained his
services and invited him to Paris where a new office,
Director cf Optics for the Marine — d'optique au
service de la Marine — T\nth a salary of 8,000 francs,
was created for him. He retained this position until
1783 when he returned to Italy to supervise the
