216 Intelligence and Miscellaneous Articles, 



scribed in which corresponding structure, sometimes coupled with 

 a similar mineral constitution, may be met with. Difficulties 

 attending the determination of the origin of some clastic rocks were 

 also pointed out, and the value of certain structural characters in 

 their diagnosis were mentioned. Assumptions as to the origin of 

 some fragmentary rocks were shown to be undemonsfcrable in certain 

 cases, although such assumptions often carried much probability 

 with them. The resemblances presented by de vitrified rhyolitic 

 rocks, felstones, and felspathic grits were dwelt upon at some length. 

 The paper included a short structural classification of the con- 

 stituents of rocks. 



2. " Distribution of the Serpentine and associated Eocks, with 

 their Metallic Ores, in Newfoundland." By Alexander Murray, Esq., 

 C.M.G., P.G.S. 



The author stated that no extensive display of serpentine is 

 known in the Laurentian series in Newfoundland ; nor is the existence 

 of crystalline limestone of that age, with which serpentine is often 

 associated, as yet well established. The Intermediate or Huronian 

 system is singularly barren in lime, magnesian minerals, and mica, 

 lime occurring almost exclusively as intersecting calcareous veins. 

 Over all the known area of the system no masses of serpentine have 

 been observed, and only one instance of the presence of a serpen- 

 tinous mineral, which occurs in an intrusive mass intersecting the 

 Intermediate system and disturbing the outcrop of the sandstones 

 of the Primordial Silurian (Lingula Mags) at a place called " The 

 Broad " of Tickel Harbour, Trinity Bay, where some steatite with 

 some seams of asbestos were seen near the contact. Wherever a 

 typical fossiliferous horizon could be established, the stratigraphical 

 position of the fossils placed those of the Levis age, or older, below 

 the serpentines ; while in all cases, where the types were of Hudson- 

 River or newer date, they as invariably succeeded unconformably 

 above. Instances of this unconformable relation were mentioned in 

 which the upper formation was as late as the Devonian age. The 

 stratigraphical and palaeontological break between the Levis and 

 Trenton groups is here filled up by a metamorphic mass which, in 

 part at least, may possibly represent the horizon of the Chazy group ; 

 and the great intrusive masses have been connected with, or the 

 cause of, the metamorphic phenomena displayed. 



XXXVII. Intelligence and Miscellaneous Articles. 



ON THE ELECTROMAGNETIC THEORY OF THE REFLECTION AND 

 REFRACTION OF LIGHT. BY GEORGE FRANCIS FITZGERALD, 

 M.A., FELLOW" OF TRINITY COLLEGE, DUBLIN. 



rPHE media, at whose surfaces reflection and refraction are sup- 

 -*- posed to take place, are assumed to be nonconductors, and isotropic 

 as regards magnetic inductive capacity. Some reasons are advanced 



