2 INTRODUCTION. 



and splendor of the objects, the inconceivable rapidity 

 with which they move, and the enormous distances 

 between them, impress the mind with some notion of 

 the energy that maintains them in their motions, with a 

 durability to which we can see no limit. Equally con- 

 spicuous is the goodness of the great First Cause, in 

 having endowed man with faculties, by which he can 

 not only appreciate the magnificence of His works, but 

 trace, with precision, the operation of His laws, use the 

 globe he inhabits as a base wherewith to measure the 

 magnitude and distance of the sun and planets, and 

 make the diameter (Note 1) of the earth's orbit the 

 first step of a scale by which he may ascend to the 

 starry firmament. Such pursuits, while they ennoble 

 the mind, at the same time inculcate humility, by show- 

 ing that there is a barrier which no energy, mental or 

 physical, can ever enable us to pass : that, however 

 profoundly we may penetrate the depths of space, 

 there still remain innumerable systems, compared with 

 which, those apparently so vast must dwindle into in- 

 significance, or even become invisible ; and that not only 

 man, but the globe he inhabits nay, the whole system 

 of which it forms so small a part might be annihilated, 

 and its extinction be unperceived in the immensity of 

 creation. 



A complete acquaintance with physical astronomy 

 can be attained by those only who are well versed in 

 the higher branches of mathematical and mechanical 

 science (N. 2), and they alone can appreciate the ex- 

 treme beauty of the results, and of the means by which 

 these results are obtained. It is nevertheless true, that 

 a sufficient skill in analysis (N. 3) to follow the general 

 outline to see the mutual dependence of the different 

 parts of the system, and to comprehend by what means 

 the most extraordinary conclusions have been arrived 

 at, is within the reach of many who shrink from the 

 task, appalled by difficulties, not more formidable than 

 those incident to the study of the elements of every 

 branch of knowledge. There is a wide distinction be- 

 tween the degree of mathematical acquirement neces- 

 sary for making discoveries, and that which is requisite 

 for understanding what others have done. 



