37 



South gave him access to his observatory, and thus enabled him to 

 familiarize himself with the use of instruments. 



But it is to Professor Wallace, ever his steady friend, under 

 whose care the Observatory of the Edinburgh Astronomical Institu- 

 tion was then placed, that he owed his rapid progress in astronomy, 

 if not his ultimate adherence to the science. Finding in Mr Hen- 

 derson a zeal for the study, and an ambition to distinguish himself 

 in it, Mr Wallace, with his accustomed disinterestedness, unhesi- 

 tatingly placed the Observatory at his command, and thus afforded 

 him the means of acquiring that practical skill for which he was 

 celebrated. To this circumstance I attribute much of Mr Hender- 

 son's success in astronomy. However true it be, that talent will 

 develope itself in spite of obstacles, it is no less certain, that, in sciences 

 like this, which owe so much to the external aid of expensive instru- 

 ments, the fortuitous circumstance of an access to the requisite 

 machinery, is a strong stimulus to exertion, without which few 

 would undergo the drudgery of acquiring a mastery of the practical 

 details of the science. With an observatory at his disposal, Mr 

 Henderson saw the road to eminence in practical astronomy open 

 before him, and he hesitated not to labour zealously to fit himself 

 for the walk to which his inclinations prompted him. 



As might be supposed, he had not long entered on a systematic 

 course of reading, ere improvements suggested themselves to his 

 acute mind. The first which he made public, relates to the compu- 

 tation of an observed occultation of a fixed star by the moon. This 

 he transmitted to Dr Thomas Young, then secretary to the Board 

 of Longitude in 1824. It was published by him in the Nautical 

 Almanac for 1827 and the four following years ; and Mr Henderson 

 received the thanks of the Board for his communication. This 

 paper, and many others of his, were likewise inserted in the Qicar- 

 terly Journal of Science. It is probable that the subject which 

 actually brought Mr Henderson into notice with astronomers, was 

 his detection of an error in the data furnished to Mr Herschel for 

 the determination of the difference of longitude of London and 

 Paris. His paper on this subject was published in the Philo- 

 sophical Transactions for 1827, and the Royal Society voted him 

 a copy of the Greenwich Observations, in return for his labour. 

 This communication had also the effect of procuring for him the 

 friendship of Mr Herschel, whose estimate of its importance is 

 expressed in a testimonial which he gave Mr Henderson in 1829, 

 when candidate for the chair of Practical Astronomy, in the following 

 VOL. II. E 



