30 FKAGMENTS OF SCIENCE. 



ton to our own time, eager eyes have been scanning 

 the heavens, and clear heads have been pondering the 

 phenomena of the solar system. The same eyes and 

 minds have been also observing, experimenting, and re- 

 flecting on the action of gravity at the surface of the 

 earth. Nothing has occurred to indicate that the 

 operation of the law has for a moment been suspended; 

 nothing has ever intimated that nature has been 

 crossed by spontaneous action, or that a state of things 

 at any time existed which could not be rigorously de- 

 duced from the preceding state. 



Given the distribution of matter, and the forces in 

 operation, in the time of Galileo, the competent mathe- 

 matician of that day could predict what is now occur- 

 ring in our own. "We calculate eclipses in advance, 

 and find our calculations true to the second. We de- 

 termine the dates of those that have occurred in the 

 early times of history, and find calculation and history 

 in harmony. Anomalies and perturbations in the 

 planets have been over and over again observed; but 

 these, instead of demonstrating any inconstancy on the 

 part of natural law, have invariably been reduced to 

 consequences of that law. Instead of referring the 

 perturbations of Uranus to any interference on the part 

 of the Author of nature with the law of gravitation, 

 the question which the astronomer proposed to him- 

 self was, ' How, in accordance with this law, can the 

 perturbation be produced?' Guided by a principle, 

 he was enabled to fix the point of space in which, if a 

 mass of matter were placed, the observed perturbations 

 would follow. We know the result. The practical 

 astronomer turned his telescope towards the region 

 which the intellect of the theoretic astronomer had 

 already explored, and the planet now named Neptune 

 was found in its predicted place. A very respectable 



