202 Proceedings of the Asiatic Society. [Aucj. 



coast, succeeded in navigating these vessels. They are for the most 

 part uneducated natives of the country. They are entirely unacquainted 

 with such instruments as are generally in use for determining the 

 position of a vessel at sea. They have no chronometers, and no 

 sextants. Indeed being strictly coasting vessels, they do not leave 

 sight of land, unless, as is not unfrequently the case, they are com- 

 pelled by stress of weather to do so. On enquiry I found that they 

 used a very ingenious but rudely simple means of obtaining approxi- 

 mately a knowledge of their latitude, when thus driven from shore. 

 They do not care for any knowledge of their longitude, and never think 

 of this. 



The little contrivance which I now exhibit, consists simply of a 

 small rectangular thin board or piece of teak-wood. The one I have 

 measures 3J inches long by 2£ inches broad, and is about T T ¥ inch 

 thick. Through a small hole in the centre of this, determined by 

 the intersection of the diagonals, a fine cord is passed, about the 

 thickness of fine whipcord. The use of this little instrument depends 

 upon the fact that the latitude of any place is roughly the same as 

 the angle of elevation above the horizon of the polar star, and that any 

 opaque object held vertically before the eye subtends an angle, which 

 varies inversely as the distance of the object from the eye. If this dis- 

 tance be constant, and the size of the opaque object constant, the angle 

 subtended by it must be constant also. Knowing this, the application of 

 contrivance I hold in my hand is simple. The small rectangular board is 

 held firmly in the left hand, while the cord from its centre (held in the 

 right hand), is stretched from it to the eye, where the fingers of the 

 right hand are held. As this cord, or the distance from the eye to 

 the small rectangular board, is increased or diminished, so is the angle 

 subtended by the opaque board, lessened or enlarged. Well, say the 

 Captain of one of these coasters is anchored at Vizagapatam, on the 

 coast, he takes advantage of a clear night, and sitting on the deck of 

 his vessel, he carefully brings the line of the lower edge of this small 

 rectangular board to coincide with the line of the horizon, or sea line, 

 and moves the board slowly back and forward, until he brings the 

 line of the upper edge to correspond with or to intersect the polar star. 

 Carefully marking the length of the cord passing from his eye to the 

 board, when this is the case, he puts a knot on the cord at that point. 



