FERGUSON'S LECTURES. 



To find the mean time of full moon in any given year and 

 mouth after the Christian J&ra. 



Having collected the moon's mean motion from the 

 sun for the beginning of the given year and month, and 

 subtracted their sum from 12 signs (as in the former 

 example) add 6 signs to the remainder, and then pro- 

 ceed in all respects as above. 



EXAMPLE II. 



Required the mean time of full Moon in September, 1 764 ? 



Moon from sun. 

 s o ' 



To the year after Christ's 'birth 1753 10 9 24 56 

 Add complete years .. 11 01014 20 



(sum 1764) 

 And join September ...... 2 22 21 8 



The sum of these mean motions is . . 1 12 24 

 Which, being subtract, from a circle, or 12 



Leaves remaining ....... 10 17 59 36 



To which remainder add ..... 6000 



And the sum will be 4 17 59 36 



Next less mean motion for 11 d. subtract 4 14 5 54 



And there remains 3 53 42 



Next less mean motion for 7 h. subtract 3 33 20 



And the remainder will be .... 20 22 

 Next less mean motion for 40m. subtract 20 19 



Remains the mean motion for 8 sec. 0003 



So, the mean time, according to the tables, is the llth 



