400 FERGUSON'S LECTURES. 



LECT. Moon from sun. 



XIL a o ' 



-x " v " x>/ Leaves remaining 11 25 4 57 



Next less mean motion for 29 days, subt. 11 23 31 54 



And there remains . 1 33 3 



Next less mean motion for 3 hours subt. 1 31 26 



And the remainder will be .... 1 37 

 Next less mean motion for 3 min. subt. 1 31 



Remains the mean motion of 14 seconds 0006 



So, the mean time by the tables, was the 29th of 

 May, at 3 hours 3 min. 14 sec. past noon. A day later 

 than the truth, on account of its being in a leap-year. 

 For as the year of CHRIST 1. was the first after a 

 leap-year, the year 585 before the year 1, was a leap- 

 year of course. 



If the given year be after the Christian JEra, divide 

 its date by 4, and if nothing remains, it is a leap-year 

 in the old stile. But if the given year was before the 

 Christian ^ra, or Year of CHRIST 1, subtract one 

 from its date, and divide the remainder by 4 ; then, if 

 nothing remains, it was a leap-year ; otherwise not. 



To find whether the sun is eclipsed at the time of any given 

 change, or the moon at any given full. 



Oieclipses. From the Table of the sun's mean motion or distance, 

 from the moon's ascending node, collect the mean motions 

 answering to the given time ; and if the result shews 

 the sun to be within 18 degrees of either of the nodes 

 at the time of new moon, the sun will be eclipsed at that 

 time. Or, if the result shews the sun to be within 12 

 degrees of either of the nodes at the time of full moon, 

 the moon will be eclipsed at that time, in or near the 

 contrary node ; otherwise not. 



