GALILEO AND HIS JUDGES. 71 



influence over the Earth, and the Earth again over the 

 Moon, but they did not know that the Moon attracted 

 the Earth exactly in the same way, though with far 

 inferior potency, owing to her much smaller mass ; 

 and consequently they were not aware of the Moon's 

 power to raise the great tidal wave in the ocean, to 

 which are due the remarkable phenomena so familiar 

 to the inhabitants of the English coasts. 



Galileo would have been wise if he had not touched 

 on a point which he neither understood in theory, nor 

 had properly acquainted himself with by practical obser- 

 vation. Good causes are often damaged by bad argu- 

 ments, and such was the case on this occasion.* There 

 was, however, something ingenious in his argument. 

 If you take a basin of water, and move it along quite 

 smoothly and evenly, no great commotion in the 

 water takes place ; but suppose some stoppage or 

 jerk to occur, the result will be, as we know, very 

 different. Now the Earth has two motions, one 

 round its axis in twenty-four hours, and the other 

 round the Sun in one year ; every point, then, on the 

 Earth's surface moves through space more rapidly 

 while on that side of the globe which is turned away 



* It is not intended here to deny what some writers state that 

 the friction caused by the Earth's rotation does in some degree 

 act upon the tidal wave. It is remarkable, so far as can be 

 ascertained from observations taken at some small island at a 

 distance from any continent, that the tidal wave of the Ocean only 

 rises, even at the spring, about five or six feet. The enormous 

 rise of water at some places arises from the tidal wave being 

 driven into estuaries, mouths of rivers, and other narrow channels. 



