same uniformity.... if the line described by a falling body is not exactly this, it is very near to it... [and] according to these considerations, straight motion goes entirely out the window and nature never makes any use of it at all. Riccioli explained that this conjecture could not work: It could not apply to the fall of bodies near the Earth's poles, where there would be little or no circular motion caused by Earth's rotation; and even at the equator where there would be more motion caused by Earth's rotation, the rate of fall predicted by Galileo's idea was too slow. Riccioli argued that the problems with Galileo's conjecture were a mark against the Copernican world system, but modern writers differ in regards to Riccioli's reasoning on this. The "coriolis effect" argument Riccioli also argued that the rotation of the Earth should reveal itself in the flight of artillery projectiles, because on a rotating Earth the ground moves at different speeds at different latitudes. He wrote that If a ball is fired along a Meridian toward the pole (rather than toward the East or West), diurnal motion will cause the ball to be carried off [that is, the trajectory of the ball will be deflected], all things being equal: for on parallels of latitude nearer the poles, the ground moves more slowly, whereas on parallels nearer the equator, the ground moves more rapidly. Therefore, were a cannon, aimed directly at a target to the north, to fire a ball, that ball would strike slightly to the east (right) of the target, thanks to the Earth's rotation. But, if the cannon were fired to the east there would be no deflection, as both cannon and target would move the same distance in the same direction. Riccioli said that the best of cannoneers could fire a ball right into the mouth of an enemy's cannon; if this deflection effect existed in northward shots they would have detected it. Riccioli argued that the absence of this effect indicated that the Earth does not rotate. He was correct in his reasoning in that the effect he describes actually does occur. It is known today as the Coriolis effect after the nineteenth-century physicist Gaspard-Gustave Coriolis (1792–1843). However, the rightward deflection actually occurs regardless of the direction the cannon is pointed (a much more developed understanding of physics than what was available in Riccioli's time