7i6 THE POPULAR SCIENCE MONTHLY. 



times corresponding to each pointing were recorded, and the designation of the 

 object observed was also marked on the paper disks, so that there is no ditSculty 

 in identifying the several marks. 



He then goes on to give the particulars of his sweeps over the re- 

 gions east and west of the sun, which were without result till, at last — 



Between the sun and e Cancri ... I came across a star estimated at the 

 time to be of four and a half magnitude, which shone with a ruddy light and 

 certainly had a larger disk than the spurious disk of a star. The focus of the 

 eye-piece had been carefully adjusted beforehand and securely clamped, and the 

 definition was excellent. I proceeded, therefore, to mark its position on the 

 paper circles, and to record the time of observation. It was designated by a. 

 The place of the sun had been recorded a few minutes previously, and marked Su 

 Placing my eye again at the telescope, I assured myself that it had not been dis- 

 turbed, and proceeded with the search. I noticed particularly that the object 

 in question did not present any elongation such as would be probable were it a 

 comet in that position. 



This body he holds to be Leverrier's intra-Mercurial planet. Its place 

 is given as follows : 8^- 26"- 24^- ; declination 18° 16'. It will be seen 

 that this position differs from that given above, the declination being 

 here 18° 16', instead of 18° 0'. 



On August 23d the observer added a new^ correction : " In conse- 

 quence of having employed an inexact value for the correction of the 

 chronometer, an error has crept into the results. The true position is 

 this : right ascension, S*"- 27'°- 35^ ; declination, 18° 16'." 



Here we have a fresh difference in the first figure. The result is, 

 first, that the orbit calculated immediately upon receipt of the telegram 

 was made too hastily and on an insufficient basis. 



According to the American observer, the definitive differences be- 

 tween the planet and the sun were : in right ascension, 8"- 21"- ; in dec- 

 lination, 0° 22'. But in this same letter of August 23d he announces 

 that he observed another star, also of the fourth magnitude, which pre- 

 sented the following differences from the sun : in right ascension, 27"' 

 18"-; in declination. 0° 35'. "Whence results for this second star the 

 position : right ascension, 8'"' S"' 38'' ; declination, 18° 3'. 



A fourth datum sent to the London Royal Astronomical Society 

 again corrects these positions as follows : 



gh. 27m. 24- 4. 18° 16' 

 gh. 9m. 24- + 18° 3' 



We will remind our readers that the right ascension of a star is its 

 distance east or west from the first point of Aries, measured along the 

 celestial equator, and its declination is its distance above or below that 

 equator. They are the longitudes and latitudes of the heavens, corre- 

 sponding to those of earth, and they serve to determine the positions 

 of stars as earth longitudes and latitudes serve to fix in geography the 

 exact positions of cities. 



