238 W. Dennis on the Theory of the Tides. 
around the earth being a fact as familiar to most as that of the 
earth around the sun. But action and reaction being always 
equal, while the earth holds the moon to its course or orbit i 
ner attracted and held by the moon to an extent proportioned t0 
its inferior size or mass, and the consequence is that both bodies 
against what seems to be a very common misconception 0! 
revolution of the earth about this point. This material error 
Consists in supposing that point in the earth where this cenulv 
lies, or which coincides with this centre at any instant, to be md 
honary as regards this revolution, while the other parts of # 
