Amongst the tables appended to the "American Practical Navigator" are two tables, 5A and 5B, which have for their object the determination of the distance of the ship from a fixed point of which two bearings have been taken, the course and distance run between the observations having been carefully noted. But it is pointed out in the body of the work that the fix obtained by two bearings of the same object will be in error unless the course and distance are correctly estimated, the course "made good" and the distance "over the ground" being essential to accuracy in the result, and the utility of such tables, having regard to the difficulty of estimating accurately the effects of wind and current, is very greatly restricted. An extension of the same problem has recently been proposed, whereby, if a third bearing of the same object is added, the course "made good" over the ground may be deduced, upon the assumption that the speed of the ship has been uniform during the interval covered by the observations, and that the effect of wind and current has also remained fairly constant during the same period.
A New Method in Coastal Navigation
By H. B. Goodwin