108 



A perpetual Moon Table. 



[No. 134, 



TABLE II. 



This table requires but little explanation. The 

 first column shews full centuries. That marked 

 N. S. shews the place in half days on the circum- 

 ference of the card, of the mark for adjusting the 

 N. S. centuries to the mark of ® on the outer 

 card. In like manner the columns headed O. S. 

 and B. C. or — shew the places of the marks for 

 adjusting the cards by, in centuries of O. S., or in 

 those before the Christian era. ♦ 



These observations may suffice for shewing the 

 general construction of this card ; the reason for giv. 

 ing the century marks their particular position re- 

 mains to be stated. 



According to the Synopsis of Astronomy in Bar- 

 low's Tables, (which, and his Dictionary, were the 

 only books of reference within my reach when ar- 

 ranging this Table) the Moon's mean longitude on the 

 1st of Jan. 1801, was 3s. 21° 36' 42", or 1 1 1° 36' 42" 

 that of the sun being 9 10 09. 13, or 280 09 13 



Hence the moon was then distant ) 



from the sun, J 191 27 29 



or 11° 27' 29" past the full. This at the rate of 

 29^ days to a lunation, gives the Moon's age on the 

 1st of January 1801 as 15° 66' 11". Barlow's data 

 being taken from Laplace's Systeme du Monde, are 

 probably adapted to the meridian of Paris. The dif- 

 ference between Paris and Greenwich is 9m. 21.5s. 

 corresponding in lunation days to .00643. Greenwich 

 being to the west of Paris, this must be added to 

 15° 66' 11", in order to have the Moon's mean age at Greenwich on 1st 

 January 1801. As for the convenience of keeping the same digits 

 throughout a century, I reckon from 1800, the Epact for a year of 

 365 days must be deducted; this is lOd. 15h. 11m. 24s. which re- 

 duced at the rate of 89.50s. daily, becomes lOd. 14h. 55m. 33s. = lOd. 

 5219, and this taken from 15d. 66 1 1 + 00643, leaves 5d. 14 56 as the 

 Moon's mean age in lunation days at Greenwich on the 1st January of 

 1800. In half days this is 10'29 ; as in the Table. 



g 



N. S. 



O. S. 



B.C. 



or — 







17.29 



13.29 



13.29 



1 



' 6.62 



4.62 



21.96 



2 



54.96 



54.96 



30.62 



3 



44.29 



46.29 



39.29 



4 



35.62 



37.62 



47.96 



5 



24.96 



28.96 



56.62 



6 



14.29 



20.29 



6.29 



7 



3.62 



11.62 



14.96 



8 



53.96 



2.96 



23.62 



9 



43.29 



53.29 



32.29 



10 



32.62 



44.62 



40.96 



11 



21.96 



35.96 



49.62 



12 



13.29 



27.29 



58.29 



13 



2.62 



18.62 



7.96 



14 



50.96 



9.96 





15 



40.29 



1.29 



25.29 



16 



31.62 



51.62 



33.96 



17 



20.96 



42.96 



4262 



IS 



10.29 



34.29 



51.29 



19 



58.62 



25.62 



0.96 



20 



49.96 



16.96 



9.62 



21 



39.29 



8 29 



18.29 



22 



28.62 



58.62 



26.96 



23 



17.96 



49.96 



35.62 



24 



9.29 



41.29 



44.29 



25 



57.62 



32.62 



52.96 



26 



46.96 



23.96 



2.62 



27 



36.29 



15.29 



11.29 



28 



27.62 



6.62 



19.96 





16.96 



56.96 



28.62 



30 



6.29 



48.29 



37.29 



33 



54.82 



39.62 



45.96 



32 



45.96 



30.96 



54.62 



33 



35.29 



22.29 



4.29 



34 



24.62 



13.62 



12.96 



35 



13.96 



4.96 



21.62 



36 



5.2J 



55.29 



30.29 



37 



53.62 



46.62 



38.96 



38 



42.96 



37.96 



47.62 



39 



32.29 



29.29 



56.29 



40 



21.62 



20.62 



5.96 



41 



10.96 



11.96 



14.62 



n 



0.29 



3.29 



23.29 



43 



48.62 



53.62 



31.96 



44 



39.96 



44.96 



4062 



45 



29.29 



36.29 



49.29 



4C 



18.62 



27.62 



57.96 



47 



7.96 



18.96 



7.62 



48 



5S.29 



10.29 



16.29 



41 



47.62 



1.62 



24.96 



50 



36.96 



51.96 



33.62 



