362 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 15 



Besides being blanketed with a layer of air, which is the domain of 



meteorology and "the weather," the Earth is also covered in large 



part with a thin layer of water, from a few inches to several miles 



deep — the ocean. The geography of the ocean, the science which 



treats of the distribution, the physical properties, and the tides and 



currents of the ocean is known as oceanography : 



Murray, John. The ocean. 256 pp. (Henry Holt & Co., New York, 

 about 1913.) An interesting, non-technical, yet thoroughly reliable account 

 of the methods, instruments and results relative to the depths, temperatures, 

 physical properties, tides, currents and plant and animal life in the ocean. 



The structural units of the solid earth — the "bricks" of which it 



is built — are the rocks, whose composition, properties, and origin 



form the subject matter of petrology : 



Cole, Grenville A. J. Rocks and their origins. 175 pp. Cambridge 

 Manuals of Science and I^iterature. (Cambridge University Press, England, 

 1912.) Neither abstruse nor popular, but adapted to a well-informed reader 

 rather than a beginner. The treatment is unbiased and thoroughly scien- 

 tific, and covers the whole field, though briefly. It is logical, thorough, accu- 

 rate, and stimulating; readable, but not catchy. There is no other book 

 in the field of just the same sort, for comparison. 



The constituent crystals or particles which make up the rocks 

 .'including the valuable ores) form the subject of "mineralogy" — from 

 ^ne point of view a branch of chemistry : 



Bennett, Lee F. Rocks and minerals. Third edition. SS pp. (Bo- 

 garte Book Co., Valparaiso, Indiana, 1914.) An excellent little elementary 

 book, describing in an interesting way 40 minerals and 40 rocks. Suited to 

 give the general reader with a minimum of time at his disposal a good idea 

 of the scope of the sciences of mineralogy and petrology. 



Gratacap, Louis P. A poptilar guide to minerals. 330 pp. (D. Van 

 Nostrand Co., New York, 1912.) A splendidly illustrated work, based on the 

 collections in the American Museum of Natural History in New York City. 

 The text is not up to the standard of the plates, being rather chmisily put 

 together, although reasonably accurate and elementary in most places. 

 Will appeal to the users of books who gain more from illustrations than from 

 text matter. 



The oldest of the sciences, and still the one with the most permanent 

 popular appeal, notwithstanding the fact that its 5000-year competitor 

 from the field of superstition — astrology — is still active, is astronomy : 



Abbot, Charles G. The sun. 448 pp. (D. Appleton and Co., 1911). 

 The best book on the subject of the Sun; readable, though technical in places. 



Ball, Robert S. The story of the heavens. 556 pp. (Cassell and Co., 

 London, 1892.) Delightfully written, and in popular language. 



Dyson, F. W. Astronomy. '247 pp. (E. P. Dutton and Co., New York, 

 1918.) Elementary, yet thoroughly reliable. 



Hale, George E. The study of stellar evolution. 252 pp. (University 

 of Chicago Press, 1908.) An interesting, well illustrated, and authoritative 

 summary of results relating to the constitution of the stars and the Sun. 



