132 SIR JOHN FREDERICK WILLIAM HERSCHEL. 



astronomical observer be was undeniably facile princeps, not merely 

 among tbe astronomers of bis own country, but among all bis astro- 

 nomical contemporaries. His mastery extended over tbe widest range. 

 In bis general knowledge of tbe science of astronmy he was unap- 

 ropacbed ; in tbe matbmetical department of tbe science be was proficient 

 above most ; in bis knowledge of tbe details of observatory-work be 

 was surpassed by none ; and as a ganger of tbe beavens by tbe largest 

 telescopes be dwarfs into insignificance all tbe observational work ac- 

 complisbed by astronomers living or dead. He went over tbe wbole 

 range of bis fatlier's worli: tbrongb tbe nortbern skies, and tben com- 

 pleted tbe survey of tbe beavens tliat bend over tbe soutbern bemis- 

 pbere. He alone could boast tbat no part of tbe celestial deptbs bad 

 escaped bis scrutiny. As an interpreter of natnre, be was unrivaled ; 

 as au expounder of astronomical trutbs be bad no living peer, and as 

 a tbeorist be commanded universal attention and compelled large as- 

 sent.. 



In order to be clearly understood as to tbe meaning attached to tbe 

 words " astronomical theorist,"' let us quote a passage from one of tbe 

 papers of Sir William Herschel. It is taken from that noble essay con- 

 tributed to the Transactions of tbe IJoyal Society, in which be brst pre- 

 sented bis ideas respecting the constitution of the celestial depths. 



"■ First let me mention," be says, " that if we should hope to make 

 any progress in investigations of a delicate nature, we ought to avoid 

 two opposite extremes, of which I can hardly say which is the most dan- 

 gerous. If we indulge a fanciful imagination snd build worlds of our 

 own, we must not wonder at our going wide from the path of truth and 

 nature ; but these will vanish like tbe Cartsian vortices tbat soon gave 

 way when better theories were offered. On tbe other hand, if we add 

 observation to observation, without attempting to draw, not only certain 

 conclusions, but also conjectural views from them, we otieud against the 

 very end for which only observations ought to be made." 



Sir John Herschel has also described the quality primarily requisite 

 in a tbeorist. "As a first i»rei»aration," tbe paper goes on to say, "he 

 must loosen his hold on all crude and hastily-adopted notions, and must 

 strengthen himself by something like an effort antl a resolve for the un- 

 prejudiced admission ol"any conclusion which shall appear to be supported 

 by careful observation and logical argument, even should it prove of a 

 nature adverse to notions he may have previously formed for himself, 

 or taken up, without examination, on the credit of others. Such au ef- 

 fort is, in fact, a commencement of tbat intellectual discipline which 

 forms one of tbe most important ends of all science. It is the first 

 movement of approach towards tbat state of mental purity which alone 

 can fit us for a full and steady perception of moral beauty as well as 

 physical adaptation. It is the 'euphrasy and rue' with which we must 

 ' purge our sight ' before we can receive and contemplate as they are 

 the lineaments of truth and nature." . 



