76 Scientific Intelligence. [Jan. 



room, with as little loss of heat as possible, the windows were thrown 

 open, the heating bath removed, and the effect of cooling observed. 



The flexure decreased as the bar cooled, and after it had remained 

 two hours in order to be cooled down to the temperature of the room, 

 which was 60°, the flexure had decreased three-fourths of one of the 

 divisions of the scale ; and when the weight was raised from the bar, it 

 returned through 14 divisions. Hence we may conclude that by an 

 elevation of temperature equal to 212° — 60° = 152 degrees, iron 

 loses about a twentieth part of its cohesive force, or will bend one- 

 twentieth more by the same load. This is equal to about a 3000th 

 part for each degree.— (Tredgold on Cast Iron, 2d Edit. p. 104.) 



V. Correctness of Greenwich Observations. 

 (To the Editor of the Annals of Philosophy.) 

 DEAR SIR, Blackman»rircct, Dec. 20, 1824. 



In the October number of the Annals, a notice was inserted by me, 

 wherein it was stated, " a communication has, we understand, been 

 received from Mr. Bessel, acknowledging that his catalogue of princi- 

 pal stars requires a correction for instrumental flexure, thereby admit- 

 ting the superiority of the Greenwich one." It seems, however, that 

 the accuracy of the report is by Messrs. Tilloch and Taylor contra- 

 dicted ; * upon what grounds, it is immaterial to inquire : but as a 

 charge of misrepresentation is insinuated, I shall merely state, that a 

 letter was sent by Dr. Tiarks (a German astronomer in the pay of the 

 British Government), containing an extract of a letter (translated into 

 English) which he had received from Mr. Bessel, couched in such a 

 manner as to induce the gentleman to whom it was addressed, to trans- 

 mit to Mr. Troughton a note, informing him of Mr. Bessel's 

 concession ; and which note was shown to me, as well as to many 

 others, interested in these matters. Not, however, content with 

 having done thus much, Dr. Tiarks subsequently called upon Mr. 

 Troughton, and with much apparent satisfaction, personally communi- 

 cated to him the same concession on the part of his friend ; and among 

 other things said, " Bessel had acknowledged that had he used Pond's 

 mode of observing sooner, he should have gotten his latitude cor- 

 rectli/." And at this time there can be no doubt but that Dr. Tiarks 

 considered himself justified in promulgating Mr. Bessel's acknowledg- 

 ment of the superior accuracy of the Greenwich catalogue. What new 

 light may have since broken in upon this gentleman, 1 do not pretend 

 to know ; it is right, however, the readers of the Annals should be 

 apprised, that the communication was not made to them upon slight 

 grounds. Mr. Bessel also should be informed, that whatever " idle 

 reports " (if such they at present be) have gone abroad, are of German, 

 not of British origin ; and that they have been circulated by the indus- 

 try of his own friend, and from a letter of his own writing. 



James Soeth. 



VI. British Museum and Edinburgh Revieiv. 

 The author of an article in the Edinburgh Review, on the British 



♦ Philosophical Magaxine for November la«t. 



