Latitude of a Place, hy Ohservatiom of the Pole-Star. 49 



affairs, has stated that Mr. Bowditch (in his " New American 

 Practical Navigator") has re-calculated the logarithms, tech- 

 nically called Log. Rising, and extended them to 1 2^. It may 

 perhaps be gratifying to learn that a similar extension of those 

 useful tables has also been made in this country by Captain 

 Lynn in a work entitled " Solar Tables for working the longi- 

 tude by chronometer, or for finding the latitude by double 

 altitudes of the sun or stars." In the Requisite Tables pub- 

 lished by Dr. Maskelyne, the Log. Risi7ig are carried to five 

 places of decimals, and for every 10 seconds of time. In those 

 recently published by the Rev. Mr. Lax, they are extended to 

 every 4 seconds of time, but still to 5 places of decimals only. 

 In those now publishing by Capt. Lynn, they are extended to 

 every second of time, and to six places of decimals. The work, 

 as flir as 9 hours, is already published, and wiU be equally 

 useful to the astronomer and the seaman : but, whether it will 

 be continued, or not, will probably depend on the patronage 

 which is afforded to that part which is already before the public. 

 Too great encouragement cannot be given to works of this kind, 

 which abridge so much the labour of computation. 



In deducing the time from altitudes of the sun or stars, by 



means of the strict analytical formula, we obtain sin* — as tlie 



value of the hour angle. This expression is of frequent oc- 

 currence in various astronomical solutions, and had induced 

 me to form a table of its value for every second of the quadrant. 

 By the help of Capt. Lynn's tables, however, this labour might 

 have been saved, since we have merely to add the constant lo- 

 garithm 5.3010300 to the logarithm of sin- ~, and we imme- 

 diately obtain the Log. Risitig : which, as I have already ob- 

 served, is calculated in Capt. Lynn's tables to every second ; 

 and which consequently shows, upon inspection, the correct 

 time required, without any further reduction. Its application 

 would have been more general if it had contained the values 

 of the angles in arc as well as in time ; similar to the plan 

 adopted by Mr. Lax. 



VIII. True apparent Right Ascension of Dr. Maskelyne's 36 

 Stars for every Day in the Year 1822, at the Time of passing 

 the Meridian of Greenwich. By the Rev. J. Guooby. 



[Continiictl from vol. lix. page 101.] 

 The Autlior wishes to remark tliut the hist six months of the year have 

 not !)cen ealniliifod from the same tables as the former, hut from iiiore re- 

 cent ones pnblisiied in the Konif,'si)urf,' Observations for 1818. The '"«»" 

 riRht ascension as there given by Ucssel has also been used, instead of that 

 given by Mr. Pond. 



Vol'. GO. No. 29 1 . July 1 822. G 1 822. 



