Notices of Memoirs — Yorksliire Naturalists' Union. 131 



The bearing of this conclusion upon the ultimate development of 

 the human race is so far-reaching in its consequences that the great 

 sacrifice of life attendant upon the prosecution of these researches 

 stands forever as a memorial in the correction of the erroneous and 

 widespread conception that the earth is in a period of refrigeration, 

 desiccation, and decay ; and establishes the conclusion that it is in 

 the springtime of a new climatic control during which the areas 

 fitted for man's uses are being extended and that the moss of polar 

 wastes will be replaced by rye and wheat. 



IV. — JonN MiCHKLL AND Martin Simpsou". 



SIR ARCHIBALD GEIKIE read as his Presidential Address to 

 the Yorkshire Union of Naturalists, 1917,. a memoir on John 

 Michell (1724-93), one of the pioneer geologists of this country. 

 The memoir, written in Sir Archibald's delightful style, appears in 

 full in the Yorkshire Naf/iiralist for January, 1918. 



Mr. Thomas Sheppard, remembered recently for his able memoir 

 on William Smith, read to the Yorkshire Geological Society a paper 

 on Martin Simpson (1800-92) (see Geol. Mag., Eebruarv, 1918, 

 p. 82). 



E,:E"V"iE'V\rs. 



I. — Sands used in Mandfactukes. 



1. A Memoik on British Resources of Sands suitable for Glass- 

 making, WITH Notes on certain Crushed Rocks and Refractory 

 Materials. By P. G. H. Boswell. pp. 92. London : Longmans, 

 Green & Co. 1916, 



2. A Supplementary Memoir on British Resources of Sands and 

 Rocks used in Glass-manufacture, with Notes on certain 

 Refractory Materials. By P. G. H. Boswell. pp.92. London: 

 Longmans, Green & Co. 1917. 



3. British Glass-sands; their Location and Characteristics. By 



P. G. H. Boswell. From the Transactions of the Society of 

 Glass Technology, vol. i, 1917. 



4. Notes on American High-grade Glass-sands. By P. G. H. 

 Boswell. Prom the Transactions of the Society of Glass Tech- 

 nology, vol. i, 1917. 



5. Some Geological Characters of Moulding-sands. By P. G. H. 

 Boswell. Reprinted from the Foundry Trade Journal, August, 

 1917. 



6. Sands used in Metallurgical Practice, with Comparative 

 Notes on those used in Glass-manufacture. By P. G. H. 

 Boswell. Reprinted from the Journal of the Society of Chemical 

 Industry, 1917. 



njlHE petrology of the sedimentary rocks is a subject that has been 

 JL unduly neglected until recent times. Considerable attention 

 was devoted to the matter by Professor Bonney, mainly in connexion 

 Avith cemented types which could be studied in their slices. The 

 early investigations of Retgers, Dick, Thoulet, Breon, and others may 



