Discovery of an Error in the Nautical Almanac. 61 



I shall take the liberty of copying all that I can find in 

 this book, that bears the least relation to them. It is con- 

 tained in an example at page 125, and is as follows: 



*' Exa/nph. On the first of May 1 795, ihe sun's longi- 

 tude was 1 sign 1 1'" l' 4l", and the obliquity of the ecliptic 

 23" 27' 51". Required the rest." 



71ie solution stands as follows : 



To find the Declination. 



As rad. 90'' co. arc 



To sine sun's long 41° 1'44" 9-8171947 



So is sine sun's greatest declination 23 27 31 9-6000743 



To sine present declination 13 9 7 9'41 72692 



To find the Right Ascension. 



As cot sun's lone 41° T 44" 9-939C05 3 co arc 



To rad r 10- 



So is cos obliq. ecliptic. . 23 27 31 9-9623158 



To tancr ri^ht ascension . . 38 35 31 9-9021211 



Here 38° 33' 51" turned into time, is 2^ 34' 23" 24'", the 

 right ascension in time. 



The above calculation is accompanied with the following 

 note : 



"See the Nautical Alm.anac for May 1, 1795. The 

 learner should as an exercise take out the sun's longitude 

 and declination for any other day to find the rest, so as to 

 make his calculations agree with those of the JSlaulical Al- 

 manac." 



There are besides the above, two more examples, but 

 these are to find the sun's longitude either from his right 

 ascension or declination; which 1 have omitted, because the 

 sun's longitude is always calculated as put down in the 

 Nautical Almanac, from astronomical tables which embrace 

 no less than fifteen or sixteen different equations. The 

 apparent obliquity of the ecliptic is also computed from 

 astronomical tables ; and from the sun's longitude and obli- 

 quity of the ecliptic so found, his declination and right as- 

 cension is computed by a simple case of a right- angled 

 spherical triangle. 



In the example above given, we are not inforiDed what 

 obliquity of the ecliptic is to be used, mean or apparent, nor 



are 



