270 Mr. C. Tomlinson's Further Remarks 



numerical measure of either being |Er. Thus, according to 

 the theory first mentioned, in the case of torsion of a compo- 

 site circular bar, if the couple of torsion be such that %Er 

 exceed at any distance from the axis the limit of safety, as 

 determined by tractional experiments, for the material at that 

 distance rupture will ensue. The rupture would at first be 

 limited to the single material ; and if it proceeded right round 

 would merely produce an increased strain in the remaining 

 media, which might or might not, according to circumstances, 

 produce further rupture. In practice, rupture would in all 

 probability be at first limited to a small region, and the bar 

 would undoubtedly tend to become warped. Direct experi- 

 ments on the rupture of isotropic bars by torsion may disprove 

 the above theory, but it is fairly obvious that the true law must 

 depend on the state of strain and stress in the material. Thus 

 the preceding solution will in any case supply the data that 

 may be necessary in determining the limit of safety of a 

 composite bar under torsion. 



XXXII. Further Remarks on Mr. Aitken's Theory of Dew. 

 By Chakles Tomlinson,^. j R./S'.* 



I HAD no idea that the innocent title of my paper, 

 " Remarks on a New Theory of Dew/' had a guilty 

 meaning ; but according to Mr. Aitken I " was raising a false 

 contention," and so attempting to place the author " in oppo- 

 sition to recognized authorities" ; that the results of his 

 investigation "are in no sense entitled to be called new ;" 

 and he repeatedly states that his investigation was not promul- 

 gated in opposition to the theory of Dr. Wells, but " in 

 extension of the work, the foundations of which were laid by 

 Dr. Wells." Again, he says the new theory " is not in oppo- 

 sition, nor are the results contrary to the teaching of Dr. 

 Wells." Once more, the author " never made any attempt to 

 set aside Wells's theory." 



And yet it is curious to notice that i Chambers's Journal ' 

 for May 29th last contains an article headed " A New Theory 

 of Dew," in which the writer, after giving an accurate outline 

 of Wells's theory, goes on to say that Mr. Aitken " has brought 

 forward many observations, and the results of numerous 

 experiments, which appear to prove that Dr. Wells' theory of 

 dew is not, after all, correct." We are further informed that 



* Communicated by the Author. 



