Royal Astronomical Society. Q>6 



The promptitude and accuracy with which these calculations were 

 made induced the Council to request him to communicate his me- 

 thods to the Society ; and he accordingly drew up a set of Practical 

 Rules for the Approximate Prediction of Occultations, which are 

 published in vol. iv. of the Memoirs. These services were duly 

 acknowledged in our Annual Reports ; and at the anniversary meet- 

 ing in 1830 the thanks of the Society were voted to him " for the 

 very valuable assistance he had rendered to the cause of astronomy 

 in his various computations presented to the Society." _. 



The amount of Mr. Henderson's contributions to astronomy fronl' 

 1825 to 1830, consisting of observations, tables, remarks, methods, 

 and calculations of various kinds, published in the Quarterly Jounial 

 of Science, the Nautical Almanac, and the Notices and Memoirs of 

 this Society, would have done credit to a professed computer ; but in 

 order rightly to appreciate his zeal, it must be remembered that he 

 was all this while occupied with professional duties of a kind which 

 would be found by most persons to be sufficiently engrossing. His 

 disinterestedness was no less remarkable than his scientific ardour ; 

 for though in the receipt of very^ moderate emoluments, he declined all 

 remuneration for his calculations ; nor would this feature of his cha- 

 racter be fully appreciated unless it were told at the same time that 

 a considerable part of his income was appropriated by him to the 

 support of his mother and sisters. '^ 



Mr. Henderson's official duties, while connected with the Earl of 

 Lauderdale and the Lord. Advocate, brought him for some months in 

 each year to LondoUj upon which occasions he became personally 

 acquainted with the principal astronomers of the metropolis, and 

 had an opportunity, particularly at the observatory of Sir James 

 South, which was freely thrown open to him, of seeing and handling 

 instruments of the first class. His various useful contributions to 

 astronomy had already acquired for him a considerable reputation; .' 

 and the high opinion which had been formed of his talents was in- 

 creased by observation of the worth and unaffected simplicity of his'' 

 character, and the range and extraordinary accuracy of his informa- 

 tion on all astronomical subjects. Accordingly, a prospect of attach- 

 ing him to an office by which his services would be secured for the ' 

 exclusive benefit of astronomy, afforded satisfaction to all those who 

 took an active interest in the progress of our science. 



The death of Dr. Robert Blair, in December 1828, having caused a 

 vacancy in the professorship of Practical Astronomy in the University 

 of Edinburgh, Mr. Henderson's qualifications for that office were re- 

 presented to the Government (the patrons of the appointment) by Dr. ' 

 Thomas Young, and energetically urged by some other astronomers, 

 particularly by Captain Basil Hall. From the correspondence which 

 passed with the Secretary of State, it appears that the Government 

 upon that occasion postponed the filling up of the vacancy in order that 

 opportunity might be given to consider upon what footing the office, 

 which had hitherto been a sinecure, could be placed with the great- 

 est prospect of advantage to science. In the summer of 1 829 another 

 astronomical appointment became vacant by the lamented death of 

 Phil Mag. S. 3. VoL 27. No. 1 77. July 1 84.5. F 



