PREFACE. 



In this publication an attempt has been made to gather 

 into one volume all of the investigations that apply to the 

 system of polyconic projections. This was undertaken 

 mainly for the reason that no such treatise has ever 

 been produced in the English language. No adequate 

 treatment even of the ordinary, or American, poly- 

 conic projection has been given in any separate publica- 

 tion. The work by Thomas Craig entitled ''A Treatise on 

 Projections/' published by the United States Coast and 

 Geodetic Survey, 1882, gives almost no treatment of the 

 polyconic projection as used by the Coast and Geodetic 

 Survey, but merely makes reference to the various vearly 

 reports of the Superintendent of the Survey for informa- 

 tion regarding it. 



The subject of projections as a whole seems to have been 

 considerably neglected bv authors who employ the English 

 language. A small wort by Arthur R. Minks, pubhshed 

 by the Cambridge University Press in 1912, is an excellent 

 introduction to the general subject, and gives promise of 

 some awakened interest in this branch of apphed mathe- 

 matics. 



In the preparation of this publication the following 

 works were especially consulted: The most excellent work 

 by M. A. Tissot, Memoire sur la Representation des Sur- 

 faces et les Projections des Cartes Geographiques, Paris, 

 1881; Traite des Projections des Cartes Geographiques, by 

 A. Germain, Paris, 1866 (?) ; Lehrbuch der Landkartenpro- 

 jektionen, by Norbert Herz, Leipzig, 1885; Notes on Stere- 

 ograj)hic Projection by Prof. W. Wl Hendrickson, U. S. N. 



It is hoped that the treatment of the various classes of 

 polyconic projections may be found complete enough to 

 serve all practical purposes. 



