1 -l 



r:j2 



KEI'ORT — 1884. 



s I- ?■.■:■ 



rp,st, therefore, on ninro .siihstiiiitiul base.i of fact.H than could have Leon suifpeeted 

 by any one iinaequaintt'd with thoxe custonis. 



This nietliofl of conil)inin<; tiu; rt'sults of fifoological Vfscavch \vitli historical 

 record.s the author has found on previous occasions to havf the advanta^'c of liiin;j. 

 iuf^ tiiB i^eolof^ist into toucli with the rest of humanity, attractinir as it doi's tlir 

 intei'est of histoi'ians, linfjuists, and otliers, wlio find in the facts so jjrescnted Id 

 them pabulum applicable to the requirements of their own particular jjursuits. 



In this juiper it will not be necessary or suituhle to enter at h-nffth into details 

 --the autlior iiaviiifT (lone so elsewhere.' His oliject is rather to direct attention 

 to the 8ul)ject f^enerally, and to make known the fact that much has been accom- 

 plished of late years, wliicli has not aa yet fciund its way into manuals and ency- 

 clopjcdias. Most of the iid'ormation to he found in such works is far Ijehiiid oiir 

 present knowledf.'e ; and, where not actually incorrect, has been su])erscdi'(l hy 

 fuller aTid more accurate* observations. The subjects taken for special considenitimi 

 are the followinfr: - Diamond, ruby, sapphire, spinel, beryl, emerald, lapis-lazuli, jiold, 

 silver. The steel of India, or iiuiotz, mijrht be included here, since at least :,',00() 

 years ago it was one of the most precious jiroductions of India. 



11. What is a Mineral ]'eiu or Loth- ? By C. Le Neve F(>stei!, B.A., 



B.Sc, F.G.S. 



The author quoted briefly the definitions of a mineral vein jjiven by Werner, 

 ( 'arne, 11. von Cotta, (Irimm, A. von (iroddeclc, ( Jcikie, Sandberger, and Serlo, wiio, 

 in common with nu)st geologists, liave looked upon mineral veins as ' the contents 

 of fissures.' "While admitting that a very large number of veins may be so described, 

 the author contended that the exceptions are sufiiciently important and numerous 

 to warrant a change in the definition. He ie of opinion that many of the principal 

 and most productive tin-lodes in Cornwall are simply tabular masses of altered 

 granite adjacent to fissures ; and he brought forward the opinions of other geologists 

 to show that certain veins in the I^iglish Lake district, the Tyrol, Nova Scotia, 

 Nevada, ('olorado, California, and Australia are not filled-up fissures. In conclusion, 

 lie proposed the following definition : ' A mineral vein or lode is a tabular mineral 

 mass formed, more or less entirely, subsequently to the enclosing rocks.' 



TUESDAY, SEVTEMliElt 2. 



'J'he following Papers and Reports were read : — 



1. T}an for the Sulject-Blhliograpli i/ of North American Geolocjij. 



By G. K. Gilbert. 



The United States Geological Survey is engaged on a Hibliograjdiy of Nortk 

 American Geology. The work -when completed will give the title of each paper, 

 with the title-])age of the containnig book, and the number of plates, the whole 

 being arranged alpliabetically by autliors. 



There is in contemplation also the simultaneous preparation of a number ot 

 more restricted bibliographies, each covering a division of geologic literature. Thi' 

 plan includes abbreviated titles of papers, with reference to the pages on which the 

 special subjects are treated, the entries in each bibliography being arraiigtHJ alpha- 

 betically by authors. 



The selection of topics for treatment in this manner involves the classification 

 of geologic science, and the author submitted a tentative classification, requesting 

 the criticisms of geologists. 



' ' Economic Geology of India,' and ' A Geologist's Contribution to the History of 

 India,' Proc. Roy. DakSoc. 1883. 



