4 



ASTRONOMY. 



[Sect, I. 



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lying in a harbour of wiiicti the latitude and the longitude 

 are well known, for observing eclipses of the sun. These 

 observations arc almost always valuable. It can seldom 

 be expected that the time of the begimung of an eclipse 

 can be observed accurately, but the time of the end of it 



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can usually be observed with very groat accuracy. And 

 if the eclipse is total, the times of beginning and end of 

 the totality can be observed accurately: if it is annukr^ 

 he times of beginning and end of the annularity can be 

 accurately observed. The observation^i should be made 

 with the largest telescope which the navigator pc^^esses ; 

 and any peculiarity of distortion of the sun's limb or the 

 moon's limb, siiy light surrounding the moon, &C-5 should 

 be carefully recorded. [If the eclipse be total, attention 

 should be paid to any coloured or other appendages pro- 



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iectino; from the dark edge of the moon, -'Iso to the 

 luminous corona surrounding the moou, its apparent 



ivith the 



breadth, and whether apparently concentric 

 moon or with the sun near the moments of beginning and 

 end of the total obscuration.] While the eclipse is in 

 progress, but especially near the beginning or the end, 

 mca. v.res of the distance between the cusps or sharp points 

 t which the moon's limb crosses the sun's hmb may be 

 repeatedly taken. In recording these observations, the 





obseryatioiis by which the time is determined, and the 

 observations bv which the index-error of the sextant is 

 determined, should be written down in the fullest detad ; 



and the unreduced observations should be givuu as well 



as the reduced observations. 



3. In similar circumstances occultations of stars l)y the 

 moon may frequently be observed. Eclipses of Jupiter s 



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