288 HISTORY OF FORMAL ASTRONOMY. 



the centre of our earth, it is credible that the sun, the moon, and the 

 other lights, have a similar affection, by which they remain round as 

 we see them ; but none of these centres is necessarily the centre of the 

 universe." 



The most obvious and important physical difficulty attendant upon 

 the supposition of the motion of the earth was thus stated : If the earth 

 move, how is it that a stone, dropped from the top of a high tower, 

 falls exactly at the foot of the tower? since the tower being carried 

 from west to east by the diurnal revolution of the earth, the stone must 

 be left behind to the west of the place from which it was let fall. The 

 proper answer to this was, that the motion which the falling body re- 

 ceived from its tendency downwards was compounded with the motion 

 which, before it fell, it had in virtue of the earth's rotation : but this 

 answer could not be clearly made or apprehended, till Galileo and his 

 pupils had established the laws of such Compositions of motion arising 

 from different forces. Rothman, Kepler, and other defenders of the 

 Copernican system, gave their reply somewhat at a venture, when they 

 asserted that the motion of the earth was communicated to bodies at 

 its surface. Still, the facts which indicate and establish this truth are 

 obvious, when the subject is steadily considered; and the Copernicans 

 soon found that they had the superiority of argument on this point as 

 well as others. The attacks upon the Copernican system by Durret, 

 Morin, Riccioli, and the defence of it by Galileo, Lansberg, Gassendi, 13 

 left on all candid reasoners a clear impression in favor of the system. 

 Morin attempted to stop the motion of the earth, which he called 

 breaking its wings; his Alee Terrce Fractal was published in 1643, 

 and answered by Gassendi. And Riccioli, as late as 1653, in his Al- 

 magestum Novum, enumerated fifty-seven Copernican arguments, and 

 pretended to refute them all : but such reasonings now made no con- 

 verts ; and by this time the mechanical objections to the motion of the 

 earth were generally seen to be baseless, as we shall relate when we 

 come to speak of the progress of Mechanics as a distinct science. In 

 the mean time, the beauty and simplicity of the heliocentric theory 

 were perpetually winning the admiration even of those who, from one 

 cause or other, refused their assent to it. Thus Riccioli, the last of its 

 considerable opponents, allows its superiority in these respects; and' 

 acknowledges (in 1653) that the Copernican belief appears rather to 

 increase than dimiuish under the condemnation of the decrees of the 

 Cardinals. lie applies to it the lines of Horace : 14 



13 Del. A. M. vol. i. p. 594. 14 Almag. Nov. p. 102. 



