NOVUM ORGANUM. 177 



of the ball is too swift to allow an impression of its figure 

 to be conveyed to the sight. 



This last instance, and others of a like nature, have some 

 times excited in us a most marvellous doubt, no less than 

 whether the image of the sky and stars is perceived as at 

 the actual moment of its existence, or rather a little after, 

 and whether there is not (with regard to the visible appear 

 ance of the heavenly bodies) a true and apparent time, as 

 well as a true and apparent place, which is observed by 

 astronomers in parallaxes.* It appeared so incredible to 

 us, that the images or radiations of heavenly bodies could 

 suddenly be conveyed through such immense spaces to the 

 sight, and it seemed that they ought rather to be transmitted 

 in a definite time. That doubt, however (as far as regards 

 any great difference between the true and apparent time), 

 was subsequently completely set at rest, when we consi 

 dered the infinite loss and diminution of size as regards the 

 real and apparent magnitude of a star, occasioned by its 

 distance, and at the same time observed at how great a 

 distance (at least sixty miles) bodies which are merely white 

 can be suddenly seen by us. For there is no doubt, that 

 the light of the heavenly bodies not only far surpasses the 

 vivid appearance of white, but even the light of any flame 

 (with which we are acquainted) in the vigour of its radiation. 

 The immense velocity of the bodies themselves which is 

 perceived in their diurnal motion, and has so astonished 

 thinking men, that they have been more ready to believe 

 in the motion of the earth, renders the motion of radiation 

 from them (marvellous as it is in its rapidity) more worthy 

 of belief. That which has weighed most with us, however, 

 is, that if there were any considerable interval of time be 

 tween the reality and the appearance, the images would 

 often be interrupted and confused by clouds formed in the 

 mean time, and similar disturbances of the medium. Let 

 this suffice with regard to the simple measures of time. 



It is not merely the absolute, but still more the relative 

 measure of motions and actions which must be inquired 

 into, for this latter is of great use and application. We 

 perceive that the flame of fire-arms is seen sooner than 

 the sound is heard, although the ball must have struck the 

 air before the flame, which was behind it, could escape : the 

 reason of which is, that light moves with greater velocity 



* This is a singular approximation to Roemer s discovery of time being; re 

 quired for the propagation of light. 



VOL. XIV. N 



