Errata in No. 250. 



Page 170, second line of table, 



for Bell-metal at 0° vibrates during 55 sees. ; at 100° it vibrates during 15 sees. 



read „ „ „ 55 „ „ „ 40 „ 



Page 171, line 27 from top, for air of glass tubes of different diameters, renders 

 read air in glass tubes of different diameters, render 



„ 173, line 11 from top, dele The frequency of the vibrations of 



„ 195, „ 12 from bottom, for from the globular read having the globular 



Erratum in No. 251. 

 Page 367, Mr. W. H. Everett's paper, in first equation, for rd 2 8 read r 2 d& 



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