LET. II. OF TllE EARTft. 2Y

And, in a manner equally easy, may anotherobjection be removed, which has frequentlybeen brought against this doctrine. It has beenasserted, that if the earth moved, a stone droppedfrom the top of a tower, or any other highbuilding, would not fall just at the bottom ofit, as the building must have advanced con-siderably forward during the time of the fall.But this is evidently a mistake; for it is wellknown, by repeated experiments, that if a bodybe projected from another body in motion, itwill always partake of the motion of that otherbody. Thus, a stone dropped from the top ofa mast, whilst the stiip is under fail, is not leftby the vessel, but falls exactly at the foot of themast. And if a bottle of water be hung up inthe cabin, with its neck downwards, it willempty itself, drop by drop, into another bottleplaced exactly underneath it, though the shipshall have run many feet whilst each drop wasin the air.

This motion of the earth round its axis,which, from the instances already given, hasbeen sufficiently proved, is called its diurnal, ordaily motion; and is that which occasions theregular return of day and night, and all thecelestial appearances before mentioned. Butthere is also another motion of the earth, calledits annual, or yearly motion, which occasionsI the