142 ASTRONOMICAL Aun 
As Mercury's heliocentric motion was in the order of the 
fines, and he had paffed the. node, fubtra& this diftance from 
his heliocentric longitude, and the remainder will be the point 
. S$ of the ecliptic, or place of Mercury's afcending node, 
—Mercury's heliocentric longitude, 15-20°26" 36" 
Subtract y's diftance from a, 4 42 16 
Place of 3’s afcending node by obfervation, I I5 44 20. 
Ditto by M. de la Lande’s tables, I Ig 45 C4 
Au 
b 
