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(%vho5e advice had been requested by the Secretary of State ), to the 

 Professorship of Practical Astronomy in the University of Edinburgh, 

 with which office was conjoined the superintendence of the Edin- 

 burgh observatory, then taken under the protection of the Govern- 

 ment. This appointment he continued to hold till his death, which 

 took place after a short illness, in consequence of an affection of the 

 heart, on the 23rd of November ISi-i, before he had quite completed 

 his 46th year. 



Professor Henderson's reputation as an astronomer stood high ; 

 he was a careful and accurate observer, an expert and resolute cal- 

 culator, was profoundly skilled in the theory of instruments, and 

 possessed great knowledge of methods, and an acquaintance with the 

 history and literature of his science, which for extent and minute 

 accuracy has rarely been surpassed. The results of his labours 

 were for the most part communicated to the Royal Astronomical 

 Society, and have been printed in their Memoirs : they embrace a 

 considerable range of subjects, but the most important perhaps, in 

 point of permanent value, is his Catalogue of the Declinations and 

 Right Ascensions of 172 principal Fixed Stars (chiefly in the south- 

 ern hemisphere), observed by himself and his assistant during his 

 residence at the Cape ; and the most remarkable of the single results 

 he obtained is a sensible parallax of the double star a Centauri, 

 amounting to about one second of space: this result, which he first 

 detected on a comparison of his reduced observations of declination, 

 was partially confirmed by the subsecjuent reduction of the observa- 

 tions of the star's right ascensions ; and it afterwards received from 

 him a further confirmation by a discussion of the observations made 

 by his successor Mr. Maclear, expressly with a view to the determi- 

 nation of the question. Having regard to the history of this subject, 

 it would perhaps be unsafe at present to affirm that he has done 

 more than establish a strong probability in favour of the measure- 

 able parallax of this system (already remarkable for its great proper 

 motion) ; but should further observations change the probability into 

 a certainty, Mr. Henderson's name will descend to posterity asso- 

 ciated with a discovery which has so long been the desire of astro- 

 nomers, and so often baffled their efforts. His whole astronomical 

 career was marked by an activity and energy which continued un- 

 abated to the last. Nor were his labours confined to the routine of 

 his official duties. On more than one occasion he cheerfully under- 

 took the heavy task of giving lectures for his colleagues in the Uni- 

 versity ; much of his time was consumed in the reduction of his Cape 

 observations ; he superintended the reduction and arrangement of 

 La Caille's Catalogue for the British Association; and if a comet 

 was anywhere observed, he was always one of the first to compute 

 and communicate its orbit. 



In his private character Mr. Henderson was distinguished by great 

 kindness of disposition, amiable manners, and warmth of affection ; 

 he was an enthusiastic admirer of excellence of every kind, and a 

 person on whose integrity, honour and high principles, every one 

 who had the good fortune to enjoy his acquaintance felt that the 



