44 THE SEARCH FOR THE PLANET NEPTUNE. [2 



Unfortunately I was not then aware of the publication of hour XXI of 

 the Berlin star-maps, and consequently had to proceed on the principle of 

 comparison of observations made at intervals. On July 30 I recorded the 

 approximate places of stars in a zone 9' in breadth, in such a manner as 

 to be sure that none brighter than the llth magnitude escaped me, which 

 a peculiar arrangement in the construction of the Northumberland Equatorial 

 enabled me to do. On August 4 I took the places of the brighter stars 

 in a zone 80' broad, and among these recorded a place of the planet. My 

 next observations were on August 12, on which day I met with a star 

 of the 8th magnitude in the zone which I had taken on July 30, which 

 did not then contain this star. This again was the planet. So exactly 

 had theory indicated the proper place for making the search, that in four 

 days only of observing I had recorded two positions of the planet. Also 

 according to the principle of search I had adopted, the observations of two 

 of those days (July 30 and August 12) were sufficient to discover it. My 

 time, however, was so occupied with comet reductions, and so little expec- 

 tation had I of discovering the planet by a brief search, that I was only 

 just preparing to map the places of the stars to see what success I had 

 had, when the announcement of the discovery reached me. My observations 

 after August 12 were purposely made early in Right Ascension for the 

 sake of being able to carry them on during a longer portion of the year. 

 Accordingly I did not again meet with the planet till September 29, on 

 which day I saw for the first time the results of M. Le Verrier's last 

 investigations. By these I was induced to return again to the theoretical 

 position of the planet, and to endeavour to detect it by the appearance 

 of a disk. In fact on the night of September 29, out of a very large 

 number of stars whose approximate places I recorded, I fixed upon one 

 which appeared to me to have a. disk, and which proved to be the planet. 

 On October 1 I had intelligence of Dr Galle's discovery. 



The foregoing account, while it shews that I cannot lay claim to any 

 discovery, may perhaps be regarded with some degree of interest. In 

 particular, the places which I have obtained for the planet on August 4 

 .and August 12, though they cannot pretend to great accuracy, for the 

 present possess a value which they will lose when accurate observations 

 have been continued for a longer period. I have, therefore, thought it worth 

 while to send them to you, and to describe in detail the manner in which 

 they have been deduced, that an opportunity may be given of judging of 

 the degree of confidence they deserve. 



