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HISTORY OF MAURITIUS, 
CHAPTER XIX. 
Astronomical Observations made on the Isle oj France, &c. &c. in the Tear 1753, 
by the Abbe de la Caille.*—Determination of the Longitude of the Island of 
Madeira , by the Eclipses of the Satellites of Jupiter , observed by M. Bory, 
Lieutenant in the Royal Navy of France, compared with those of the Abbe de la 
Caille , at the Isle of France , by M. de Lisle. 
These observations were made with the same instruments which the Abbe de 
la Caille had employed at the Cape of Good Hope. The place where he fixed them 
in the Isle of France was expressly fitted for the purpose. Though the sky is gene¬ 
rally clear in this island, it proved cloudy at the moment of the greater part of his 
most important observations; this circumstance proceeded, in a great measure, from 
the situation of the port, where the principal settlement of the island has been formed, 
which is surrounded with mountains almost always covered with clouds, which are 
dispersed by the winds, and successively cover the different parts of the sky. 
<c Article 1.—His first observation was made the 3d of May, 1753, on an eclipse 
of the Sun. Having regulated the pendulum by the corresponding heights of the 
Sun, he observed with the telesope of his sextant, which was seven feet in length, 
the phases of this eclipse. The largest phase was 8 digits 36 minutes. 
“ Art. 2.—He observed some eclipses of the satellites of Jupiter, with a telescope 
of fourteen feet in length, on the 25th of April, at 58' 38" past six in the evening. 
He repeated the'same observation of these satellites the 16th of October, at 36' 12" 
past three in the morning; on the 1st of November, at 54' 4" past one in the morn¬ 
ing; on the 1st of December, at 3 h 51' 33"; and on the 2d of January, 1754, at 
o h 7 ' 48". 
“ Art. 3.—On the 5th and 6th of May he observed the transit of Mercury upon 
the Sun. On those days the weather was very variable,- the intervening night was 
rainy, and it thundered; an uncommon circumstance in this island. 
* Extracted from the Memoirs of the Royal Academy of Sciences. 
