1835.] the Advancement of Science. 229 



almost unconsciously been long amassing, and which concern her as 

 the country of Newton and the maritime nation of the world ; for the 

 spirit of exactness is diffusive, and so is the spirit of negligence. 

 The closeness indeed of the existing agreement between the tables 

 and the observations of astronomers is so great that it cannot easily 

 be conceived by persons unfamiliar with that scienee. No theory has 

 ever had so brilliant afortune or ever so outrun experience as the theory 

 of gravitation has done. But if astronomers ever grow weary, and 

 faintly turn back from the task which science and nature command, 

 of constantly continuing to test even this great theory by observation, 

 if they put any limit to the search, which nature has not put or are 

 content to leave any difference unaccounted for, between the testimony 

 of sense and the results of mathematical deduction, then will they 

 not only become gradually negligent in the discharge of their other 

 and more practical duties, and their observations themselves and their 

 nautical almanacks will then degenerate instead of improving, to the 

 peril of navies and of honour ; but also they will have done what in 

 them lay, to mutilate outward nature, and to rob the mind of its 

 heritage. For, be we well assured that no such search as this, were 

 it only after the smallest of those treasures which wave after wave 

 may dash up on the shore of the ocean of truth, is ever unrewarded. 

 And small as those five seconds may appear, which stir the mind of 

 Bessel, and are to him a phophecy of some knowledge undiscovered, 

 l^erhaps unimagined by man, we may remember that when Kepler 

 was " feeling ," as he said," the walls of ignorance ere yet he reached 

 the brilliant gate of truth," he thus expressed himself respecting 

 discrepancies which were not larger for the science of his time : — 

 *' These eight minutes of difference which cannot be attributed to the 

 errors of so exact an observer as Tycho, are about to give us the means 

 of reforming the whole of astronomy." We indeed cannot dream 

 that gravitation shall ere become obsolete ; perhaps it is about to 

 receive some new and striking confirmation ; but Newton never held 

 that the law of the inverse square was the only law of the action of 

 body upon body, and the question is, whether some other law or mode 

 of action, co-existing with this great and principal one, may not mani- 

 fest some sensible effect in the heavens to the delicacy of modern 

 observation, and especially on modern reduction. It was worthy of 

 the British Association to interest themselves in such a subject: it 

 was worthy of British rulers to accede promptly to such a request. 

 I have been drawn into too much length by the consideration of this 

 instance of the external effects of our association, to be able to do 

 more than allude to the kindred instance of the publication of the 

 observations on the tides in the port of Brest, which has, I am informed, 

 been ordered by the French government, at the request of M. Arago, 

 and the French board of longitudes, who where stimulated to make 

 that request by a recommendation of the British Association at Edin- 

 burgh. Many other topics, also connected with your progress and 

 prospects, I must pass over, having occupied your time so long ; and 

 in particular I must waive what, indeed, is properly a subject for your 

 general committee — the consideration whether anything can be done 

 or left undone, to increase still more the usefulness of this association, 

 and the respect and good will with which it is already regarded by 



