VI PREFACE. 



It is a matter of regret that, owing to the cause just stated, less prominence 

 has been given in the tables to metric than to British units of length. On the 

 other hand, it seems probable that the more general use of British units will 

 meet the approval of the majority of those for whose use the volume is designed. 



The introductory part of the volume is divided into seven sections under the 

 heads, Useful Formulas, Mensuration, Units, Geodesy, Astronomy, Theory of 

 Errors, and Explanation of Source and Use of Tables, respectively. In pre- 

 senting the subjects embraced under the first six of these headings an attempt 

 was made to give only those features leading directly to practical applications 

 of the principles involved. It is hoped, however, that enough has been given of 

 each subject to render the work of value in a broader sense to those who may 

 desire to go beyond mere applications. 



The most of the calculations required in the preparation of the tables were 

 made by Mr. Charles H. Kummell and Mr. B. C. Washington, Jr. Their work 

 was done with skill and fidelity, and it is believed that the systematic checks 

 applied by them have rendered the tables they computed entirely trustworthy. 

 Mention of the particular tables computed by each of them is made in the 

 Explanation of Source and Use of Tables, where full credit is given also for 

 data not specially prepared for the volume. 



The Appendix to the present volume is that prepared by Mr. George E. Cur- 

 tis for the Meteorological Tables. Its usefulness to the geographer is no less 

 obvious and general than to the meteorologist. 



The proofs have been read independently by Mr. Charles H. Kummell and 

 the editor. The plate proofs, also, have been read by the editor j and while it 

 is difficult to avoid errors in a first edition of a work containing many formulas 

 and figures, it is believed that few, if any, important errata remain in this volume. 



R. S. Woodward. 

 Columbia College, New York, N. Y., June 15, 1894 



