ariety of
subjects. Among these subjects were the transit of Mercury, the Aurora
Borealis, the figure of the earth, the observation of the fixed stars,
the inequalities in terrestrial gravitation, the application of
mathematics to the theory of the telescope, the limits of certainty in
astronomical observations, the solid of greatest attraction, the
cycloid, the logistic curve, the theory of comets, the tides, the law of
continuity, the double refraction micrometer, various problems of
spherical trigonometry, &c. In 1742 he was consulted, with other men of
science, by the pope, Benedict XIV., as to the best means of securing
the stability of the dome of St Peter's, Rome, in which a crack had been
discovered. His suggestion was adopted. Shortly after he engaged to take
part in the Portuguese expedition for the survey of Brazil, and the
measurement of a degree of the meridian; but he yielded to the urgent
request of the pope that he would remain in Italy and undertake a
similar task there. Accordingly, in conjunction with Christopher Maire,
an English Jesuit, he measured an arc of two degrees between Rome and
Rimini. The operations were begun towards the close of 1750, and were
completed in about two years. An account of them was published in 1755,
entitled _De Litteraria expeditione per pontificam ditionem ad
dimetiendos duos meridiani gradus a PP. Maire et Boscovich_. The value
of this work was increased by a carefully prepared map of the States of
the Church. A French translation appeared in 1770. A dispute having
arisen between the grand duke of Tuscany and the republic of Lucca with
respect to the drainage of a lake, Boscovich was sent, in 1757, as agent
of Lucca to Vienna, and succeeded in bringing about a satisfactory
arrangement of the matter. In the following year he published at Vienna
his famous work, _Theoria philosophiae naturalis redacta ad unicam legem
virium in natura existentium_, containing his atomic theory (see
MOLECULE). Another occasion for the exercise of his diplomatic ability
soon after presented itself. A suspicion having arisen on the part of
the British government that ships of war had been fitted out in the port
of Ragusa for the service of France, and that the neutrality of Ragusa
had thus been violated, Boscovich was selected to undertake an embassy
to London (1760), to vindicate the character of his native place and
satisfy the government. This mission he discharged successfully, with
credit