INTRODUCTION. 47 



First, then, if possible, let the ship's place, for a 

 fixed time, be determined by astronomical observ- 

 ations. Then sketch immediately, and rapidly, 

 as correct a profile as possible of the coast, 

 (properly speaking, it is better to make this drawing 

 a little before, that it may be ready at the moment 

 of the astronomical determination of the place,) 

 and note down upon it the more important and 

 elevated points, with the letters of the alphabet. 

 Then, with one or two good compasses, determine, 

 by repeated observation, the precise bearing of 

 some remarkable object, which we will call a^ at 

 the left end of the drawing, and in the same man- 

 ner, that of the extreme object on the right. With 

 the octant, or a box sextant, measure quickly, one 

 after the other, the angles, «/;, «c, ad^ &c., which the 

 next marked objects, hy c, d^ and so on, to the right, 

 make with the point «, which an assistant imme- 

 diately writes down. (N. B. It is more convenient, 

 and quite sufficient, to make these observations 

 with the naked eye, and to read off the angles 

 accurately within a few minutes. The bearing of 

 the compass must be divided into degrees and 

 parts.) When this is done, the bearing of the first 

 and last points on the profile of the coast are again 

 taken with the compass. The mean of this and 

 the first determination gives the position of these 

 for the time of measuring the angles. All these 

 operations must, if possible, be completed within a 

 quarter of an hour. 



