[ ^°2 i 



by 6' of A. R. in time, when the ftar S' is on the id meridian, 

 and the interval L' S' the difference o£ A. R. which com.pared 

 with the moon's increafe of A. R. in 12H. will give the differ- 

 ence of meridian or of longitude. But while the point L is 

 coming to the 2d meridian the moon will have receded to 

 the point '■ , and when her enlightened limb arrives at the 

 2d meridian the obferved difference of A. R. between the ftar 

 and it will be " S' and the corredtion of this obferved differ- 

 ence will be " L', it is obvious this quantity will increafe 

 with the quantity L' S', and the quantity L' S' will be in the 

 diredl proportion of the increafing interval of ift and 2d me- 

 ridian, and of the moon's adual rate in her orbit. 



If the moon is not compared with any particular ftar at 

 cither meridian, but her apparent A. R. on the meridian ob- 

 ferved at each place by well regulated fydereal clocks — The 

 fame corredion of the obferved difference of A. R. is required, 

 as though her enlightened limb was compared with a given 

 fixed ftar ; for in this cafe ftie is, in fad, compared with an 

 imaginary ftar in the firft of aries, her obferved diflances from 

 which are fubjed to the fame regulations as though there was 

 a real ftar at that point in the heavens. 



It may be farther neceflary to add on this fubjed, that if 

 at the different places of obfervation the moon fliould be on 

 the oppofite fides of the ftar with which flie is compared, then 



the 



