XXXVI AN ACCOUNT OF THE 



the moon's ascending node was in the 10th minute 

 of the first degree of Aries ; and that her nodes 

 moved backward through the whole ecliptic in 18 

 years and 224 days, which was at the rate of 3 

 min. 11 sec. every 24 hours. But, as I scarcely 

 knew, in the year 1730, what the moon's nodes 

 meant, I took no further notice of it at that time. 



However, in the year 1739, I set to work at 

 Inverness ; and after a tedious calculation of the 

 slow motion of the nodes from Jan. 1690 to Jan. 

 1740, it appeared to me, that (if I was sure I had 

 remembered right) the moon's ascending node 

 must be in 23 deg. 25 min. of Cancer, at the be- 

 ginning of the year 1740. And so I added the 

 eclipse-part to my scheme, and called it The Astro- 

 nomical Rotula. 



When I had finished it, I shewed it to the Rev. 

 Mr. Alexander Mac Bean, one of the ministers at 

 Inverness, who told me he had a set of almanacks 

 by him for several years past, and would examine 

 it by the eclipses mentioned in them. We exa- 

 mined it together, and found that it agreed through- 

 out with the days of all the new and full moons 

 and eclipses mentioned in these almanacks ; which 

 made me think I had constructed it upon true 

 astronomical principles. On this, Mr. Mac Bean 

 'desired me to write to Mr. Mac Laurin, professor 

 ,of the mathematics at Edinburgh, and give him an 

 account of the methods by which I had formed my 

 plan, requesting him to correct it where it was 

 wrong. He returned me a most polite and friendly 



