INTRODUCTIOK. 



fined merely to coafttng ; and fach voyages, 

 undertaken without any other compafs than 

 what was fuppHed by an imperfect know- 

 ledge of the apparent motion of the fun and 

 ftars, certainly deferve to be known by thofe 

 who lludy the progrefe and improvement 

 of hydrography. The inftrument ufed by 

 pilots in the Indian feas for taking the 

 latitude is in the form of a chaplet, the 

 beads of which fhew the altitude of the 

 ftar« for the different places at which they 

 are to touch. The pofition of the beads^ 

 with regard to the eye and the horizon, 

 here ferves as an index. 



Much dexterity and long praaice arc 

 ueceCfary to ufe this inftrument, the impcr- 

 fedions of which muft be readily perceived 

 by thofe who have the fmaileft notion of 

 navigation. I tried feveral times at Pon- 

 dicheny to make ufe of it, but I could never 

 obtain by it the altitude pf a ftar within a 



degree 



