470 abstracts: geodesy 



of roadbed in paved streets being investigated. Through the co- 

 operation of the United States Forest Products Laboratory at Madi- 

 son, Wisconsin, measurements were also made on several sections of 

 test track on the Chicago, Milwaukee and St. Paul Railway where 

 railroad ties subjected to several different kinds of preservatives were 

 employed. The results of these measurements are given in tabular 

 and graphical form. E. R. S. 



GEODESY.- — .4 shidy of map projection in general. Oscar S. Adams. 

 Special Publication 60. U. S. Coast and Geodetic Survey Serial 

 113. Pp. 24, figs. 15. 1919. 



A study of some of the general properties of map projections is at- 

 tempted in this short publication. The intention is to illustrate in 

 simple form both the difficulties to be met with and the way in which 

 certain properties are attained at the sacrifice of other desirable features. 

 Of necessity there is always a compromise in any given method of 

 mapping, for the spherical surface of the earth cannot be truly repre- 

 sented upon a plane surface. Throughout the whole paper the aim 

 has been to present the considerations in the simplest possible terms, 

 so that the subject matter may be readily intelligible to any reader 

 without the necessity of following intricate mathematical developments 

 or, in other words, the purpose has been to present things in a popular 

 style so that he who runs may read with full understanding. The rela- 

 tively large number of illustrations should serve as aids in making clear 

 the statements of the text. O. S. A. 



GEOLOGY. — Deposits of manganese ore in Southeastern California. 

 Edward L. Jones, Jr. U. S. Geol. Survey Bull. 710-E. Pp. 24 

 (185-208), pi. I. 1919. 



This bulletin describes the manganese deposits in the desert region 

 west of Colorado River, which in 191 7 and 191 8 yielded over 6,000 tons 

 of high-grade ore and in which at least 30,000 tons is available. The 

 costs of mining, transportation to the railroads, and shipment to fur- 

 naces east of Mississippi River are high, and when high-grade foreign 

 ores are available these deposits can probably not be worked at a profit, 

 unless a nearer market can be found. 



The manganese deposits occur in veins and brecciated zones in sedi- 

 mentary and igneous rocks ranging in age from pre-Cambrian to prob- 

 ably Quaternary. 



