GALILEO AND HIS JUDGES. 55 



It took a long time to disabuse the human mind 

 of the antiquated opinion that the stars and planets 

 were set in vast movable spheres, as lamps might be 

 set in a large revolving cupola. 



One of the objections made at that time against the 

 axial rotation of the Earth was that, if it were really 

 the case, any weight dropped from a high tower 

 would fall some way to the west of the tower, on 

 account of the latter having been carried on east- 

 ward by the revolution of the Earth during the few 

 seconds the weight takes in falling,"* and that such 

 a result was contrary to experience. In those days, 

 when even the first law of motion had been barely 

 guessed at, the second law, that of the action of com- 

 bined forces on any body, was of course not generally 

 understood ; and a considerable debate as to this 

 point occurs in this same day's dialogue. Simplicio 

 has the hardihood to assert that if a stone be let fall 

 from the mast of a vessel, the vessel being in motion, 

 it falls behind the mast. Salviati, after making a 

 foolish distinction in accordance, however, with the 

 philosophical ideas then prevalent between the 

 natural motion of the Earth on its axis, and the 

 artificial motion of the vessel, asks Simplicio if he has 



* It is said that a weight dropped from the top of a very high 

 tower falls slightly to the east, because the velocity of the axial 

 rotation is greater at the summit of the tower than at its foot, 

 and the stone or ball dropped partakes of the motion of the highest 

 part of the tower from which it falls ; this is perfectly true in 

 theory; and experiments, made not only from the summits of 

 towers but also in mines, tend to confirm it. 



