Royal Astronomical Societi/. Tt 



produced an effect on his sensitive temperament from which he never 

 completely recovered. In the summer of that year he was gratified 

 by an event which afforded him at the time the liveliest pleasure, 

 and ever after formed a bright spot in his memory. This was the 

 visit to Edinburgh of Professor Bessel, whom he had always been 

 accustomed to regard as his master in science ; and for whose cha- 

 racter and writings he entertained an unbounded admiration. In 

 company with the great astronomer, and his countryman and col- 

 league, the celebrated mathematician Jacobi, he made a short excur- 

 sion to the Highlands ; and his friends well remember the delight 

 ■with which he used to recount the incidents of that journey, and re- 

 late anecdotes of his illustrious companions. 



Although his constitution was never robust, and he was occasion- 

 ally subject to low spirits, during the influence of which he would 

 express misgivings as to his hold on life, his health did not undergo 

 any visible change till the autumn of 1844, when he was suddenly 

 seized with an illness of so alarming a kind, that, happening at the 

 time to be on a visit to a friend, some days elapsed before he could 

 be removed to his own house. From this attack he partially reco- 

 vered, and hopes were entertained that he would soon be. enabled to 

 resume his usual duties ; but a relapse having occurred, he expired 

 suddenly on the 23rd of November, a few weeks before he would 

 have completed his forty-sixth year. The disease was then ascer- 

 tained to be hypertrophy of the heart ; and there can be little doubt 

 that, in the state of health induced by this organic disorder, the 

 fatigue of the nightly observations, and of climbing the steep hill on 

 the summit" of which the observatory is built, had been extremely 

 prejudicial to him, and contributed to accelerate its fatal termina- 

 tion. 



The character of Mr. Henderson as an astronomer stands high, 

 and his name will go down to posterity as an accurate observer, an 

 industrious computer, a skilful manipulator, and an improver of 

 methods in that department to which he devoted himself. Endowed 

 by nature with perceptive powers of great acuteness, and accustomed 

 by his early professional training to examine and sift the evidence 

 of every fact or statement presented to his mind, and to keep it be- 

 fore him until he had obtained a clear conception of it in all its bear- 

 ings, every acquisition he made was perfect ; and all his knowledge 

 was stored up in a memory of unusually retentive powers, in so or- 

 derly a manner, as to be always available at the moment it was wanted. 

 A sharp eye, and habits of order, regularity, and attention, enabled 

 him to become an excellent observer ; but the services for which he 

 will be remembered consist not so much in numerous and accurate 

 observations, as in the use which he made of them and the manner 

 in which he worked out their results. At the outset of his career 

 he was led (probably by the commendation of them in our Memoirs) 

 to study attentively the methods of the German astronomers, parti- 

 cularly those of Bessel and Struve, upon whose model he formed his 

 practice, and from which he never departed. All his memoirs and 

 investigations are characterised by the excellences of those illustrious 



