370 Astronomical and Nautical Collections. 



[The same Example by the Nautical Almanac] 



Alt. 18° 34' 



Alt. 19° Refr. 2'.47",7 Diff. Alt. ,16 B. 5,61 Th. ,34 



+ 5,2 — 26'= + 4,16 .24,-1,34 7°, + 2,38 



2'.52",9 1,34 



2.53,4 1,04 



DifFerence , 5.] 



iii. Observations on M. Delambre's Bemarks, relative to the 

 Problem of Jinding the Latitude, from two Altitudes, and the 

 Time between. By the Rev. John Brixkley, D.D., Profes- 

 sor of Astronomy in the University of Dublin. 



In giving, in the last number of the Astronomical and Nautical 



Collections, M. Delambre's method of finding the latitude from 



two altitudes of the sun and the lime between, a remark of his 



was inserted, containing a fundamental objection against the 



method of Douwes. It appears, however, that M. Delambre, 



in his Nouvelles Reflexions, Conn, des Terns, 1822, p. 316, has 



pursued an erroneous line of reasoning, a circumstance rare 



indeed as to that learned and illustrious astronomer. That 



objection to the indirect metliod of solving the problem is not 



founded. 



a 

 M. Delambre has the equation (p. 317), — =:cos. H — tan. \p 



sin. H, \p being a small arc. He assumes a value for H, and 

 computes both yp and (H + \p) from this same equation, and 

 finds (H + 4-) — i// = H. This surely could not be otherwise. 

 It is singular that it escaped M. Delambre, that the interval 

 between the observations disappears from his equation. 



Another point of view shows, that what he has done is not 

 relative to the method of Douwes. It is not an impossible 

 supposition to make the declinations exactly equal, and then 

 his method of computation, page 321, concludes nothing, in- 

 stead of becoming the method of Douwes. 



The usual objections to the method of Douwes are, 1. Not 

 allowing for the change of declination. This can occasion no 



