694 THE POPULAR SCIENCE MONTHLY. 



communications, written before be was twenty-one, are recorded in tbe 

 Royal Society's " Catalogue of Scientific Papers," wbicb also enumer- 

 ates twenty-one otbers between 1859 and 1874. His wonderful keen- 

 ness as an observer was signalized, wbile yet an undergraduate, by tbe 

 discovery of a comet on tbe 29tb day of April, 1856, and, four montbs 

 after graduation, by tbe discovery of a planet on tbe 20tb of October, 

 1857, wbicb, bowever, proved to bave been observed by Lutber a few 

 days before, and bas been named Aglaia. His observations of Dona- 

 ti's comet, in 1858, possess a standard value, and bis computation of 

 tbe orbit is recognized as autboritative. Tbe interest awakened by 

 tbis comet prompted to tbe preparation of " A Popular Treatise on 

 Comets," publisbed early in 1860. 



In 1860 Dr. Brtinnow resumed tbe directorsbip of tbe Observatory, 

 and young Watson was assigned to tbe cbair of Pbysics in tbe uni- 

 versity, wbicb be retained for tbree years, wben, on tbe final retire- 

 ment of Dr. Brtinnow, Watson was made Professor of Astronomy and 

 Director of tbe Observatory, a position wbicb be beld and bonored for 

 sixteen years. Scarcely bad be been clotbed witb full control of tbe 

 instruments, wben be resumed bis remarkable career of discovery. 

 Tbere seemed almost a magic in bis powers. Unrecognized celestial 

 objects seemed to crowd spontaneously upon bis notice. On Sej^tem- 

 ber 14, 1863, be made bis first independent planetary discovery. Tbis 

 was Eurynome. On January 9, 1864, be discovered tbe comet since 

 known as 1,863, VI, wbicb Respigbi, as it proved, bad already noted. 

 On tbe 9tb of October, 1865, be discovered a planet wbicb also proved 

 to bave been announced by Peters, and bas since been named lo. He 

 discovered Minerva, August 24, and Aurora, September 6, 1867. 

 During 1868 be added no less tban six minor planets to tbe solar sys- 

 tem, furnisbing tbe only instance in wbicb tbe list of planetary dis- 

 coverers presents tbe same name four times in immediate succession. 



Meantime be was engaged upon a work wbicb migbt well bave 

 engrossed all bis powers, and must bave quite exceeded tbe abilities of 

 any but a gifted matbematical genius. It was no less tban a complete 

 digest of tbe results and metbods of all tbe great writers on tbeoreti- 

 cal astronomy, and an independent development of tbe great principles 

 of tbe science. " Having carefully read tbe works of tbe great mas- 

 ters," be says in bis preface, " my plan was to j^rej^are a complete 

 work on tbe subject, commencing witb tbe fundamental principles of 

 dynamics, and systematically treating, from one point of view, all tbe 

 problems presented." Tbis broad plan, conceived by a young man of 

 twenty-eigbt, and completed wben twenty-nine, was executed witb 

 ability so commanding, tbat tbe work, on its appearance in 1869, was 

 immediately accepted as an autboritative exposition of tbe bigber 

 principles and processes of dynamical astronomy, and was made a 

 text-book at Leipsic, at Paris, and at Greenwicb. Tbe same year be 

 was sent by tbe General Government on an expedition to observe tbe 



