British Association for the Advancement of Science. 5 



made according to the method proposed by that distinguished phi- 

 losopher. The bars are too large to be employed in conjunction 

 with other magnetical apparatus. 



It is intended to combine a regular series of meteorological ob- 

 servations, with those on the direction and intensity of the terres- 

 trial magnetic force just spoken of ; and every care and precaution 

 has been adopted in the construction of the instruments. 



In conclusion, Mr. Lloyd said, that he felt it a duty to allude to 

 the liberality and zeal in the cause of science, which had been 

 evinced by the Board of Trinity College on this occasion. The 

 probable expense of the building and instruments is estimated at 

 1000^. ; and that sum was immediately allocated to the purpose, 

 when it appeared that the interests of science were likely to be 

 benefited by the outlay. 



Mr. Peacock congratulated the Section upon the prospect held 

 out to the scientific world, of having fixed magnetical observato- 

 ries erected in such places as would afford the surest promise of 

 successful co-operation, particularly when they would be placed 

 under the superintendence of gentlemen so eminently qualified for 

 the task as Prof. Lloyd. He informed the Section, that an obser- 

 vatory for magnetical observations had been erected at Greenwich, 

 and that little doubt need be entertained of the rapid advances 

 which the interesting investigations connected with this important 

 science would now receive. — Mr. Ettrick conceived, that bricks 

 would be a very improper material for the construction of a mag- 

 netical observatory. He considered the use of metals in any part 

 of the building as highly objectionable ; even copper, as fasten- 

 ings, or hinges to doors, would not be free from injurious effect. 

 He made some inquiries as to the mode of reading off, proposed 

 by Prof Lloyd. — Prof. Stevelly said, that Mr. Ettrick was unques- 

 tionably right in the objection urged against the use of bricks, but 

 Prof. Lloyd had distinctly stated, that bricks were not to be used, 

 and that experiments had been made to ascertain the precise mag- 

 netical influence, if any there was, of the kind of stone which it 

 was proposed to use. It was well, however, that Mr. Ettrick's ob- 

 servations should go abroad, for the guidance of persons not con- 

 versant with these subjects. Bricks, when built into large edifices, 

 such as the chimneys of factories, were well known to have ac- 

 quired magnetic polarity : the material from which they were 

 made must be largely impregnated with iron : the mud of rivers 



