MECHANICAL PHILOSOPHY. 435 



look out upon the starry concave, and learn how insignificant a 

 part our sun and all his attendant worlds form of the boundless 

 universe. He tells us that in the deepest abysses of space, the 

 Creator has ordained suns, and assigned to them their appointed 

 courses, which will remain unmoved by our catastrophe. Among 

 these dazzling wonders he points to many that are united into 

 systems, endued with proper movements of revolution, and chained 

 together by some attracting tie : and we are prompted to ask, are 

 these attractions similar to that which binds together the parts of 

 our own system ? Is the law of gravitation obeyed in these re- 

 mote regions of the universe ? If this be the case, we know these 

 bodies should describe conic sections round their common centre 

 of gravity, and round each other : Are then the orbits of the 

 double stars ellipses, like the orbits of our planets, and are their 

 motions in these ellipses governed by the same laws ? This inquiry 

 appears at first to involve insurmountable difficulties. The distances 

 of these bodies from one another seldom exceed a few seconds ; 

 and the changes in these distances, from which we might hope to 

 compute the orbit, are far within the limits of the errors of observa- 

 tion. But these difficulties have been surmounted by Sir John 

 Herschel. By taking as his data the observed angles of position, 

 instead of the distances, and by the happy union of graphical 

 witli analytical methods, he has obtained the orbits of several of 

 the double stars, and deduced their elements. The result of these 

 investigations has been the complete verification of the assumed 

 law; and thus the grand principle of gravitation which Newton 

 showed to belong to the bodies composing our own system is exten- 

 ded to the remotest regions of the starry universe, and found to be 

 the universal principle of the material creation. 



Before I conclude, suffer me to draw your attention for a few 

 moments to an objection often urged, and too easily credited, 

 against the value of the pursuit on which you are about to enter. 

 You will hear theory and practical knowledge contrasted together : 

 you will be taught to despise the former as vain and barren specu- 

 lation ; while the fruits of the latter its immediate application to 

 the uses of life, and the amelioration of the state of mankind, which 

 are its results will be paraded ostentatiously before you. 



In reply to this it might be enough to ask has our nature's 

 noblest part no pleasures, no cravings of its own? Is there no 

 part of our complex being which seeks truth for itself ? Are the 



