1 18 Suggestions respecting the ensuing Meeting 



cated this hypothesis two or three years ago to Sir John Her- 

 schel, as affording at least a partial explanation of the pheno- 

 menon, and moreover deducing it from a very simple cause. 



Baron von Wrede has lately published some speculations 

 upon the same subject, which at first sight seemed to me co- 

 incident with my own. But his hypothesis is different from 

 mine. He supposes the particles of iodine vapour to be mo- 

 tionless, and that they act upon the light as minute reflective 

 planes situated at small and equal distances from each other. 

 According, therefore, to the usual laws of the interference of 

 luminous waves, some are transmitted and others destroyed, 

 according to the length of their undulations compared with 

 the distance between the particles of vapour. 



XIV. Suggestions respecting the ensuing Meeting of the British 

 Association for the Advancement of Science. By A Corre- 

 spondent. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 f T , HE meeting of the British Association which was held 

 ■** last year in Edinburgh, will long be remembered with 

 pleasure, for the warmth with which its objects were patron- 

 ized, and for the friendly feelings and liberal hospitality so 

 uniformly evinced to the members. 



We are next month to visit our open-minded and kind- 

 hearted neighbours the Irish; and I look forward with the 

 most lively satisfaction to the occasion. Our institution has 

 made some splendid acquisitions in the sister isle ; for some 

 of the most worthy and talented of her sons have been among 

 the first and most anxious to give it their sanction. We owe 

 much to the character and abilities of these gentlemen; but 

 still more to their zeal and energy, which have so nobly se- 

 conded the exertions of the founders of the British Association, 

 and have thus given an impulse to the society, of which every 

 one is happy in feeling and in acknowledging the influence. 



I trust, therefore, that the assemblage in Dublin will be 

 ample; and that there will be a general disposition manifested 

 among the more influential of our members to make every 

 effort to attend it*. The invitation has been cordial, and its 



* We add a note to inform our readers of the kind and public-spirited 

 resolution of Sir John Tobin to devote the finest steam-vessel in the pert of 

 Liverpool to the accommodation of such Fellows of the Royal Society, 

 being also members of the Association, to whom it may be convenient to 

 proceed from thence to Dublin on the 9th of August. The communication 

 by which we are authorized to make known this most liberal invitation has 

 just reached us, and will be found among the Correspondence, on the cover 

 of the present Number. — Edit. 



