CHAP. VII.] COAST-LINING 191 



on the water-line, they will never come amiss, as long as the 

 position is well fixed. 



The officer coast-hning will make a note of anything General 

 worth recording in the sailing directions, as little nooks JfJn™^' 

 for landing, convenient places for watering, etc., letting his Direc- 

 captain know on return on board, in order that they may ^°^^' 

 be, if necessary, again looked at, or entered in the latter's 

 notes. 



It may be convenient to keep a book for the purpose, in 

 which any useful information can be entered. 



It is very useful to know the angle subtended by different Approxi- 

 parts of the hand extended at arm's-length. ™^*^ 



For instance, from the tip of the thumb to the tip of the ment of 

 httle finger will be found to subtend an angle of about 20°. ^£^^^/ 

 With the fist closed and thumb extended the angle is about the Hand 

 15° ; and from the tip of the thumb to the nearest outline of at Arm^s- 

 the hand is about 5°, The fist closed subtends an angle of length, 

 about 10°. 



By the aid of some such measurements as these carefully 

 determined and committed to memory, any angle may be 

 measured within surprisingly small limit of error. 



The entrance being fixed in the ordinary manner, the tri- sketch 

 angulated " points " are frequently lost to view on entering the Siu"vey of 

 sound. A bearing or angle being drawn to the farthest point and 

 of land visible up the sound from the innermost position where p^^°^j. 

 it is possible to fix on the outside " points," a patent log base Sound. 

 run to that farthest point will give data upon which to sketch 

 in the intermediate coast on each side, if proper angles are 

 taken at. each end of the patent log base. The survey of the 

 sound is continued in a similar manner for the whole of its 

 length on a succession of patent log bases. Great care should 

 be taken to ensure that a sketch carried out in this way does 

 not get out in bearing. 



As an instance of the application of the ten-foot pole method. Further 

 we may mention the following, which is adapted for use on ^^^ ^f^ 

 shores with fringing coral reefs, or broad sand or mud fiats, Ten-Foot 

 which dry sufficiently at low water to enable people to walk ]yi° thod. 

 on them, and when either the steepness of the hills or the 

 denseness of the vegetation prevents marks being fixed on the 

 coast. 



