+ ■- 



:ncct. 1.3 



ASTRONOMY. 



^ * 



1 



t . 



♦ 1 



\ + 



¥ 



1 



41 



me 



k or 1. 

 oft 



C 



a 



iv 



1 , 



1 '., 



1 



1 Hi 



i^ 



rr 

 e 



cll 



1] 



n ri- 



written a reference to the observations by which the index- 

 rror was determined : and in the last column should be 





written the distance as corrected. For the altitudes^ the 



the depression of the horizon, and the 



height of the 



V-- V v^ 



J ^^5 



altitude corrected for depression, should also be stated. 

 At some convenient place, either at the beginning or at 

 the end of all, should be written out all the measures bv 

 which the index-error was ascertained, exactly in the 

 manner in which they were made, and so that any other 

 person can deduce from them the value of the index-error. 

 The time of making every 



observation should 



be 



entered exactly as it is read from the chronometer or 

 hack-watch. By the side of this should be placed the 

 error of the chronometer or hack-watch on Greenwich 

 time, or on time at the ship (as may be most convenient) 

 and, after this, the corrected time. 



? 



At some convenient place, either at the beginninfr or 

 the end, must be written out all the observations by which 

 the error of the chronometer is ascertained. If its error 



on Greenwich time is given, the longitude of the ship 



must also be given, and the means and observations by 

 which tliat longitude has been determined must be 

 at length. 



If a hack-watch is used, the comparison of the hack- 

 watch with the chronometer must be given. 



The last observations by v/hich the latitude was deter- 

 mined, and the course and rate of sailing of the ship, 



must also b" 



jven. 



All the observations should be sent in this detail to the 

 Admiralty or other body appointed to receive them. 

 2. Opportunities will sometimes occur, when a ship is 



b2 



T^- - 







^ 



^ 



