July 28, 1911] 



SCIENCE 



125 



The Optical Properties of Crystals with a 

 general introduction to their physical 

 properties, being selected parts of the 

 Physical Crystallography. By P. Geoth, 

 Professor of Mineralogy and Crystallog- 

 raphy in the University of Munich. 

 Translated (with the author's permission) 

 from the fourth revised and augmented 

 German edition by B. H. Jackson, M.E., 

 M.A., of the University of Colorado. 8vo, 

 xiv -j- 309 pages, with 121 figures in the 

 text and two colored plates. Cloth, $3.50. 

 New York, John Wiley & Sons; London, 

 Chapman & Hall, Limited. 1910. 



This is a partial translation of the well- 

 known work of Professor von Groth, " Physi- 

 kalische Krystallographie," which is gener- 

 ally regarded by those who have to deal with 

 optical crystallography as the best non- 

 mathematical treatise on this subject yet pro- 

 duced. The translation, to quote from the 

 translator's prefatory note, " is made up 

 chiefly of matter contained in Part I. of the 

 original work, on the properties of crystals; 

 besides embracing the general introduction 

 and all that falls under the heading optical 

 properties in this part, it includes also what- 

 ever may be found there on the influence of 

 other properties on the optical properties. 

 Short extracts from Parts 11. (Systematic 

 Description of Crystals) and III. (The 

 Methods of Crystal Investigation) have been 

 introduced, on occasion, for illustration and 

 example." 



The scope of the work may be gathered 

 from the headings of the principal divisions 

 which are as follows: General Introduction 

 to the Properties of Crystals; The Nature of 

 Light; Combination (Interference) of Plane- 

 polarized Light; Optically Isotropic Bodies; 

 Double Eefraction of Light; Optically Uni- 

 axial Crystals; Optically Biaxial Crystals; 

 Recapitulation : Classification of Crystals 

 According to their Optical Properties; Com- 

 binations of Doubly Eefracting Crystals 

 to show the Character of their Double 

 Refraction ; Rotation . of the Plane of Polari- 

 zation of Light in Crystals; Absorption of 



Light in Crystals; Influence of other Proper- 

 ties on the Optical Properties of Crystals in- 

 . eluding Thermal Properties, Elastic Strain by 

 Mechanical Forces and by Electrical Eorces, 

 Permanent Strain, and Twinning. 



The translation is excellent, the English 

 being free and idiomatic but following closely 

 the original text. The work is entirely within 

 the comprehension of any student who knows 

 the rudiments of crystallography and forms a 

 much-needed and very welcome addition to 

 the English text-books in the field covered 

 by it. 



The colored plates reproduced from the 

 original work are excellent; I comprises a 

 spectrum of white light and a Newtonian 

 color scale of the first four orders; II pre- 

 sents the important types of interference fig- 

 ures in convergent light in thirteen figures. 



An appendix contains a useful list of Ger- 

 man and American supply houses for appa- 

 ratus, models, crystals and preparations. 

 English firms might well have been added to 

 this list. 



Charles Palache 



SPECIAL ASTICLES 



WEST ELIZABETH, PENNSYLVANIA, DEEP WELl' 



I AM indebted to Dr. I. C. White,^ state 

 geologist of West Virginia, for calling my at- 

 tention to the omission from my paper pub- 

 lished in Science, May 26, 1911, under the 

 title " Underground Temperatures," of an 

 important deep boring made in 189Y in Alle- 

 gheny County, Pa. The data relating to this 

 well are so important as to be worthy of a 

 separate note. 



The well is located on Peter's Creek about 

 two and one half miles west of West Eliza- 

 beth, Allegheny County, Pa., and about twelve 

 miles south-southeast of Pittsburgh. It is 

 the deepest well drilled in the United States 



^ White, I. C, West Virginia Geological Survey, 

 Vol. 1(A), 1904, pp. 103-107. Hallock, W. 

 ' ' Subterranean Temperatures at Wheeling, W, 

 Va., and Pittsburg, Pa.," School of Mines Quar- 

 terly, 1897, Vol. XVIII., pp. 148-153; see espe 

 cially pp. 151-153. 



-Personal communication, June 6, 1911. 



