266 A CENTURY OF SCIENCE 



23 Weed and Pirsson, e. g. Shonkin Sag, the Journal, 12, 1-17, 1901. 



-* The references for the articles mentioned (all in the Journal) are as 

 follows : 



Becker, 46, 1893; 4, 257, 1897; 3, 21-40, 1897. 



Cross, 39, 657-661, 1915. 



Adams, 22, 95-123, 1906; 29, 465-487, 1910. 



Daly, 22, 195-216, 1906; 26, 17-50, 1908. 



Wright, 22, 224-230, 1906. 



Fenner, 29, 217-234, 1910. 



Bowen, 39, 175-191; 40, 161-185, 1915. 



Pirsson, 50, 116-121, 1895; 7, 271-280, 1899. 



Smyth, 36, 33-46, 1913. 



Murgoci, 20, 133-145, 1905. 



Barrell, 13, 279-296, 1902. 



Lindgren, 3, 301-314, 1897; 9, 269-282, 1900. 



Eansome, 5, 355-375, 1898. 



Cross, 4, 115-141, 1897. 



Hague, 1, 445-457, 1896. 



Pogue, 28, 218-238, 1909. 



Warren, 25, 12-36, 1908. 



Goldman, 39, 261-288, 1915. 



Washington and Pirsson, Belknap Mts., 20, 344-353, 1905; 22, 439-457, 

 493-515, 1906. 



, Ked Hill, 23, 257-276, 433-447, 1907. 



, Tripyramid Mt., 31, 405-431, 1911. 



25 Quantitative Classification of Igneous Rocks, Cross, Iddings, Pirsson 

 and Washington, Chicago, 1903. 



Petrogenesis, C. Doelter, Braunschweig, 1906. 



Igneous Eocks, vols. 1 and 2, J. P. Iddings, New York, 1909 and 1913. 



Problem of Volcanism, Iddings, New Haven, 1914. 



Natural History of Igneous Rocks, Alfred Harker, London, 1909. 



Igneous Rocks and their Origin, R. A. Daly, New York, 1914. 



26 Among these may be mentioned: 



Rosenbusch u. Wiilfing, Physiog. der petrog. wicht. Min., Stuttgart, 1905. 

 Iddings, J. P., Rock-Minerals, 1st ed., New York, 1906. 

 Johannsen, A., Manual of Petrographic Methods, New York, 1914. 

 Winchell, N. H. and A. N., Elements of Optical Mineralogy, New York, 

 1909. 



27 Wright, Methods of Petrographic-Microscopic Research, Carnegie Inst., 

 Washington, 1911, and various papers; many in the Journal. 



28 Conf . Wright 's work quoted above and the various manuals previously 

 mentioned. 



29 Kemp, Hand-book of Rocks, 3d ed., New York, 1904. Pirsson, Rocks 

 and Rock-Minerals, New York, 1910. 



30 Williams, G. H., U. S. Geol. Surv., Bull. 62, Washington, 1890. 



31 Van Hise, Treatise on Metamorphism, U. S. Geol. Surv., Monograph 17. 



32 F. W. Clarke, U. S. Geol. Surv., Bull. 591, 1915. 



33 Hillebrand, Analysis of Silicate and Carbonate Rocks, U. S. Geol. Surv., 

 Bull. 422, 1910. 



34 Washington, Chemical Analysis of Rocks, pp. 200, New York, 1910. 



35 Id., Chemical Analyses of Igneous Rocks (1884-1900), U. S. Geol. Surv., 

 Prof. Paper, No. 14, 1903. 



36 Osann, Beitr. zu chem. Petrogr., II Teil. Anal. d. Eruptivgest., 1884- 

 1900, Stuttgart, 1905. 



37 Washington, ibid., 2d ed., U. S. Geol. Surv., Prof. Paper 99, pp. 1216, 

 1917. 



