Intelligence and Miscellaneous Articles, 481 



rock under the drift is an argillaceous shale ; and here and there are 

 outcrops of a siliceous conglomerate. The diamonds have hitherto 

 been worked only at the surface. The author mentions the principal 

 minerals found associated with the diamonds, which are generally 

 small, and their crystalline forms not very well developed. He also 

 remarks on the general accordance in the geological constitution of 

 various diamantiferous districts. 



7. " Remarks on the working of the Molar Teeth of the Dipro- 

 todon." By Gerard Krefft, Esq., P.L.S. Communicated by the 

 President. 



In this paper the author criticised a figure of the lower molars of 

 Diprotodon, published by Professor Owen, on the ground that the 

 teeth are represented in it in an unabraded state, and stated that 

 when the last tooth breaks through the gum the first of the series 

 is always worn flat. He also remarked on the peculiar modification 

 of the premolar in the genus Diprotodon. 



LVI. Intelligence and Miscellaneous Articles, 



ON THE SPECTRUM OF THE AURORA. 



To the Editors of the Philosophical Magazine and Journal* 



Gentlemen, 

 AM obliged to Dr. Marshall "Watts for pointing out the errors 

 in the wave-lengths of the oxygen- and carbon-lines as compared 

 in my paper. I am aware that in spectrum No. II. of the " Index * 

 j is given as 5602 ; but I assumed this to be a misprint for 5622, as 

 these last figures appear in spectrum No. I. against the same scale- 

 reading, viz. 58. The wave-lengths in the blue and green were 

 accidentally transposed. The true reading will therefore stand 

 thus : — 



Yellow. Green. Blue. 



Dr. Yogel's oxygen-lines 5603 5189 4829 



Dr. Watts's carbon-lines . . 5602 5195 4834 



I am aware of the frequent impurity of vacuum-tubes ; but it is 

 hardly probable all the oxygen-tubes examined were impure. 



Dr. Vogel, too, does not hint at any suspicion of his tube, which, 

 as I have said, agrees with mine very closely. 



I am, &c, 



J. Band Capron. 

 Guildford, May 1, 1875. 



Phil. Mag. S. 4. Vol. 49. No. 327. June 1875. 2 L 



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