RECENT ADVANCES IN SCIENCE 569 



888£ ft., the only useful effect being to provide additional 

 stratigraphical information upon the district. The incident 

 shows how necessary it is, in order to prevent waste and dis- 

 appointment, that exploratory borings of any kind should be 

 made under the direct supervision of the Geological Survey. 



M. C. Campbell has written a general introduction to a 

 comprehensive report on the coal resources of the United 

 States, which is in preparation in view of the growing demand for 

 fuel, and of the probability that the United States may soon 

 be called upon to supply less favoured countries (" The Coal- 

 fields of the United States," U.S. Geol. Survey, Prof. Paper 

 100-A, pp. 1-33). The estimated quantity of unmined coal 

 within 3,000 feet of the surface is 3,538,554,000,000 short tons. 



In a general review of the oil-shale possibilities of the 

 United States, D. E. Winchester has examined material from 

 formations ranging in age from the Devonian to the Eocene 

 (Econ. Geol. 19 17, 12, 505-18). The richest shale belongs to 

 the Green River formation (Eocene), which underlies an exten- 

 sive area in Colorado, Utah, Wyoming, and Nevada, and 

 compares favourably in quality with the Scottish material. 



Prof. P. G. H. Boswell has published A Supplementary 

 Memoir on British Resources of Sands and Rocks Used in Glass 

 Manufacture, with Notes on Certain Refractory Materials (Long- 

 mans, Green & Co., 191 7, pp. 72), which gives all the information 

 acquired since the publication of his first memoir in 191 6. The 

 survey of British resources of glass sands is now fairly exhaus- 

 tive. Collateral inquiries into deposits containing constituents 

 such as potash and alumina, essential to the glass industry, 

 have been made. The possibilities of crushed rocks in glass 

 manufacture have been more completely investigated, and a 

 description is given of the commoner American glass sands. 



Prof. Boswell promises a further work dealing with foundry 

 sands, and in two preliminary papers on the subject (Journ. 

 Soc. Chem. Industry, 191 7, 36, pp. 21 reprint ; The Foundry 

 Trades Journal, August 191 7, pp. 16 reprint) he emphasises the 

 importance of mechanical analyses, and of the chemical 

 analysis of the grades present, rather than the bulk chemical 

 composition of the sands. 



A large amount of geological work is included in the account 

 of the discussion upon refractories by the Faraday Society 

 {Trans. Faraday Soc. 191 7, 12, 1-189). Prof. Fearnsides writes 



