TOL. II.] PHILOSOPHICAL TRANSACTIONS. fO^ 



the equator, descend to the earth with a velocity constantly increasing as they 

 fall. But if the earth were moved by a diurnal motion only about its own 

 axis or centre, no heavy bodies dropped through the air in a perpendicular 

 direction would descend to the earth with a real and remarkable increase of 

 velocity, but with an apparent one only. Therefore the earth either does not 

 move at all, or at least not with a diurnal motion. — 2d. If the earth were 

 moved by a diurnal motion, or even by an annual one, the force of a cannon 

 ball would be much weaker, when discharged towards the north or south, than 

 from the west towards the east. But the consequent is false; and therefore the 

 antecedent also. — 3d. If the earth were moved by a diurnal rotation, a ball of 

 baked earth of eight ounces let drop through the still air from the height of 240 

 Roman feet, would fall obliquely towards the earth, without real or physical in- 

 crease of velocity, or certainly not by so much as is the proportion of the per- 

 cussion and sound occasioned by the fall from the said altitude. But the latter 

 is absurd, and therefore the former. 



In answer to the first of these arguments, Angeli denies the minor, which 

 Riccioli pretends to prove thus : — If the earth is moved by a diurnal motion, 

 any heavy body dropped from the top of a tower C, in the plane of the equator, 

 should describe by its own natural motion a portion of the line C T I, which 

 would be to all appearance circular. See fig. 6, pi. 7* 



This Angeli denies, showing, by computation, that Riccioli's observation 

 proves no such thing. For, (says Angeli) according to Riccioli, in one second 

 of an hour the weight descends 1 5 feet ; in two seconds, (X) feet ; in three 

 seconds, 135 feet; and so continually, the spaces from the beginning in the 

 duplicate proportion cf the time from the beginning; and, according to the 

 same author, AB, the semidiameter of the earth, is 25870000 feet, and B C, 

 the height of the tower of the Asinelli, in Bononia, 240 feet ; therefore A C is 

 25870240, which has the same proportion to FS, 15 feet, to wit, the fall in 

 one second, which AC, in parts 20000000000, has to FS 11 596 J'^\W% ; but 

 supposing, with Riccioli, C S I A a semicircle, F S is 53 parts, of which A C 

 is 10000000000: hence Angeli concludes, that CSIA is no ways near to a 



course concerning a New Planet; tending to prove that our earth is one of the planets. In l641. 

 Mercury, or the secret and swift messenger; showing how a man may, \n ith privacy and speed, com- 

 municate his thoughts to a friend at any distance. In this work are descriptions of many Axays of tele- 

 graphic communications, as practised by several people. In 1648, Mathematical Magic; bemg a re- 

 lation of the wonders effected by engines and mechanical contrivances. And lastly, in \66s. The 

 .Essay towards a real Character and Philosophical Language; a very ingenious performance. Besides 

 numerovis theological writings. All the foregoing mathematical and philosophical works were col- 

 lected, and published 1708, in one vol. Svo. with an account of the lile and writings of tlie author. 



