HISTORY OF MAURITIUS. 
309 
CHAPTER XIII. 
Instructions for sailing to India by the Isles of France and Bourbon.—An Account 
of the Winds that prevail in the Eastern Ocean.—A Memoir on this Archipe- 
lago , and the Dangers to which Ships are particularly subject , to the North and 
North-East of Madagascar and Mauritius , by M. D’Apres de Mannevillette. 
“V essels which are bound to the Isle of France, after having doubled the Cape 
of Good Hope, must keep to the east, on the parallel of 35 0 to 36° of latitude, till 
by 55 0 of east longitude; from thence they must take their course to the east-north¬ 
east, and then to the north-east. They will at length gain the parallel of 26° of lati¬ 
tude, by 6i° of longitude ; that is, north and south of the Island of Rodriguez. 
“ From this last position, they will make good their course to the north, to 20° of 
latitude. In navigating in this manner, the great errors which have arisen from, 
the reckoning of the longitude will be evident,, and they will not fail to reach the 
object of their destination. 
“ An attentive observation to the variation of the compass, procures the same 
advantage in the Indian seas, as to the west of the Cape. Its variations appear to 
keep such a proportion between them, in going from the west to the east, or from 
the east to the west, that they may be considered as the means of discovering the 
same errors in the reckoning. 
“ The variation was about 20° north-west at the Cape of Good Hope; it increases 
towards the east, as much as to 2.7 0 ; and this, the greatest variation, is found almost 
north and south in the middle of the Mozambique Straits. It then lessens in going 
to the east;, but I was not able to make such a succession of observations as to enable, 
me to form an instructive table. In the year 1757, I observed that the variation 
was 11° 15' at the Island of Rodriguez; and I remarked that in this part of the Eastern 
ocean, the same line of variation extended almost from south-east to north-west. 
“ The bank, which I have traced upon my chart to. the south of the straits of Mo¬ 
zambique, was discovered in the year 1748, by a ship belonging to the Dutch East 
India Company, called the Van Capel, in going from the Cape to the Isle of France, 
in 37 0 20' south latitude, and 20° 20' east from the Cape of Good Hope. This 
