362 NAVIGATION. 



that the commander or officers even of the private ships iff 

 India are unacquainted with the use of the sextant and 

 chronometer, by means of which, in clear weather, the ship's 

 true position can always be ascertained. When there are 

 three chronometers on board agreeing, great reliance may 

 be placed on them ; but lunar observations ought never to 

 be neglected, for their use may suddenly be required when 

 the practitioner is not prepared to place confidence in his 

 skill, from want of habit. The following routine is recom- 

 mended to all navigators on long voyages : — 



" Take two sets of observations for the time every fore- 

 noon and afternoon ; take sights for and work the latitude 

 by double altitudes every day ; take lunars whenever the 

 ■ moon is in distance with objects east and west of her ; ob- 

 serve the magnetic variation every twenty-four hours, let 

 each ofhcer who has charge of a watch be bound to ascer- 

 tain the latitude by stellar observations at least once every 

 twenty-four hours. Let the dead reckoning for practical 

 purposes be always deduced from the ship's last true posi- 

 tion, as ascertained by observation." 



Navigators are gTeatly indebted to Captain Thomas 

 Lynn, of the honourable company's service, for his ad- 

 mirable work on navigation, called " Lynn's Tables." He 

 is the person appointed by the East India Company to ex- 

 amine young officers in nautical astronomy, and he clso 

 conducts a naval academy with infinite credit to himself. 

 Captain Lynn recommends stellar observations to be taken 

 in the twihght of morning and evening, when the horizon 

 is generally clear and well defined.* 



It is material to observe that Madras is sixty miles west 

 of Flag-staff Point, and the easternmost part of Ceylon is 

 in about lat. 7° north. In the north-east monsoon the cur- 

 rent sets at times strong to the southward, but is liable to 

 be obstructed. In the south-west monsoon the current 

 along the Coromandel coast runs to the northward ; and 

 therefore ships bound for Madras or any other place on this 

 coast should make the land to the northward or southward 



* An admirable and very simple method of computing the latitude by 

 double altitudes is that of Mr. Samuel Dunn, which is mentioned by 

 Captain .Lynn in his " Horary Tables" lately published. Captain L. 

 lias given arguments exactly suited to the solution of this problem in 

 bis " Aiimutb Tables." 



