256 ' -• . ■ ' A NEW METHOD OF 



solar time, then the corrected interval is to be diminished in proportion to 

 twenty -four hours. Thus, if the interval is 6" : 29"" 59', in mean solar time, 

 and the daily difference of equation of time, (which is the retardation of ap- 

 parent on solar time) 14% the correction would obviously be as 24'' : 14* :: 6" : 

 59' : 3'. 25, because 6" : 29"" : 59% mean solar time, is equal to only 6*" : 29" : 

 55^. 75, of apparent time, but this quantity in apparent time is equal to the 

 sun's distance in right ascension from the meridian at the time of the transit 

 of the moon's limb, and therefore, the sun's right ascension at that apparent 

 time, plus, this distance from the meridian, is equal to the right ascension 

 of the meridian at the same instant, equal to the right ascension of the moon's 

 limb, at that instant. 



One or two examples will be sufficient, — and one set of observations will 

 generally give the longitude within 10' or 15% when the proper precautions 

 are used. 



OBSERVATORY AT PROME. 



17th November. 



H. M. S. 



The sun passed the meridian per chronometer, 12: 40: 29. 2 



Moon's limb, ditto ditto, 6:51:55.0 



Interval per chronometer, ...... ... 06: 11: 25. 8 



Rate 2. 5 in 24\ ... ' 1 n. 



Interval in mean solar time, ... ... 06: 11: 26. 5 



By reduction, the daily difference of the equation of ^ 



time is 12% 5 per day, and in 6" : U™ an apparent day,). — — 3. 7 



is = 24: 00: 12. 5 solar time, 



§un's meridional distance, 



6: 11 : 22. 8 



