HISTORY OF MAURITIUS. 
385 
Extracts of various Observations made by the Abbe de la Caille y during the Course 
of three different Passages , in his Voyages to the Cape of Good Hope , and to the 
Isles of France and Bourbon. 
“ Article 2 .—On the variation of the needle. 
“ The easterly and westerly variations are attentively observed on ships at sea, 
whenever there is an opportunity, as well to correct the courses, as to rectify the 
longitude. It is well known that there are many land-falls, which are ascertained 
by the variation of the compass; such as the Cape of Good Hope, and the Isles 
of Rodriguez, of France, and of Bourbon. It were to be wished that the va¬ 
riations observed in all ships which make long voyages, and particularly to the 
Indies, were collected and carefully registered: by this means, from time to time, 
for example, every ten years, a new edition might be given of the marine charts, 
where the curves of the variations might be marked, in the manner of M. Halley, 
as well for the year of the edition of the charts, as for an epocha of ten preceding 
years. These charts would be of great use in methodising the tracks, and, in many 
cases, they would give the longitude to land-falls with much greater certainty than 
by any observation of the moon made at sea. The proprietors of armed vessels 
should take care also to provide their ships with a good compass; and navigators 
should have somewhat less confidence in their reckoning, when they perceive that 
they do not agree with the variation. (See the tables of variation following this 
observation, pages 101 , 102 , 103 , &c. of the Memoirs of the Academy, anno 1754 .) 
“ Art. 5 .—Observations made at the Isle of Bourbon. 
“ They were made at St. Denis, which contains the principal establishment of 
the India Company. There I employed my quadrant of three feet radius, a tele¬ 
scope of fourteen feet, and a good pendulum with seconds.*’ 
