MlllACLES AND SPECIAL PROVIDENVKS. 363 



from which distances must be measured to bodies attracted 

 by the earth. 



From experiments executed before his time, Newton 

 knew the amount of the earth's attraction at the earth's 

 surface, or at a distance of 4,000 miles from its center. 

 His object now was to measure the attraction at a greater 

 distance, and thus to determine the law of its diminution. 

 But how was he to find a body at a sufficient distance? 

 He had no balloon? and even if he had, he knew that any 

 height to which he could attain would be too small to 

 enable him to solve his problem. What did he do? He 

 fixed his thoughts upon the moon a body 240,000 miles, 

 or sixty times the earth's radius, from the earth's center. 

 He virtually weighed the moon, and found that weight to 

 be one thirty-six hundredth of what it would be at the earth's 

 surface. This is exactly what his theory required. I will 

 not dwell here upon the pause of Newton after his first calcula 

 tions, or speak of his self-denial in withholding them because 

 they did not quite agree with the observations then at his 

 command. Newton's action in this matter is the normal 

 action of the scientific mind. If it were otherwise if 

 scientific men were not accustomed to demand verification 

 if they were satisfied with the imperfect while the perfect 

 is attainable, their science, instead of being, as it is, a 

 fortress of adamant, would be a house of clay, ill-fitted to 

 bear the buffetiugs of the theologic storms to which it is 

 periodically exposed. 



Thus we see that Newton, like Torricelli, first pondered 

 his facts, illuminated them with persistent thought, and 

 finally divined the character of the force of gravitation. 

 But, having thus traveled inward to the principle, he 

 reversed his steps, carried the principle outward, and 

 justified it by demonstrating its fitness to external nature. 



And here, in passing, I would notice a point which is 

 well worthy of attention. Kepler had deduced his laws 

 from observation. As far back as those observations 

 extended, the planetary motions had obeyed these laws; 

 and neither Kepler nor Newton entertained a doubt as to 

 their continuing to obey them. Year after year, as the 

 ages rolled, they believed that those laws would continue 

 to illustrate themselves in the heavens. But this was not 

 sufficient. The scientific mind can find no repose in the 

 mere registration of sequence in nature. The further 





