Prof. Challls's Observations relative to the New Planet. 24I 

 Experiment 28 (continued). 



The results of the above table show that the length of the 

 tube was diminished, in order to make up for the increase of 

 its diameter, which, in this instance, was in the direction of the 

 polarity. The quantity of the shortening effect, viz. 3*4, is 

 however only one-third of that due to the maximum elongation 

 of soft iron bars as observed in the first section. This is pro- 

 bably owing to the grain of the iron being in cross directions 

 with respect to the polarity in the two cases ; and partly per- 

 haps to the iron tube not being fully saturated with magnetism. 

 The experiment is worth repeating, especially as it affoi'ds a 

 means of studying the magnetic condition of closed magnetic 

 circuits. 



XXXIX. Second Report of Proceedings in the Cainhridge 

 Observatory relating to the New Planet {Neptune). Bi/ the 

 Rev, J. CuALLis, M.A., Plumian Professor of Astronomy 

 in the Universitxj of Cambridge'* . 



IN conformity with a wish expressed by the Vice-Chancellor 

 ■'■ and the Observatory Syndicate at their ordinary terminal 

 meeting, held on March 15, I propose in this report to carry 

 on, for the information of members of the senate, the account 

 of proceedings in the observatory relative to the new planet, 

 a first report of which was made on December 12 of last year. 

 The theoretical grounds on which a search for the planet was 

 instituted, the manner in which the search was conducted, and 

 the degree of success that attended it, were stated in the former 

 report, which brought the history of proceedings down to the 

 date at which the planet was discovered. I have now to give 

 an account of the subsequent observations both of its position 

 in the heavens, and of its physical appearance, and to state the 

 • Communicated by Professor Challis. 

 Phil, Mag. S. 3. Vol. 30. No. 201. ^pril 1847. S 



