VI PREFACE. 



In its preparation the advantage of conformity with the recently 

 issued hiternational Meteorological Tables has been kept steadily in view, 

 and so far as consistent with other decisions, the constants and methods 

 there employed have been followed. The most important difference in 

 constants is the relation of the yard to the metce. The value provi- 

 sionally adopted by the Bureau of Weights and Measures of the United 

 States Coast and Geodetic Survey, 



i metre = 39.3700 inches, 



has been used here in the conversion-tables of metric and English 

 linear measures, and in the transformation of all formulae involving 

 such conversions. 



A large number of tables have been newly computed ; those taken 

 from the International Meteorological Tables and other official sources 

 are credited in the introduction. 



To Prof. Wm. Libbey, Jr., especial acknowledgments are due for 

 a large amount of attention given to the present work. Prof. Libbey 

 had already completed a revision, involving considerable recomputation, 

 of the meteorological tables contained in the last edition of Guyot's 

 Tables, when it was determined to adopt new values for many of the 

 constants, and to have the present volume set with new type. This 

 involved a large amount of new computation, which was placed under 

 the direction of Mr. George E. Curtis, who has also written the 

 text, and has carefully prepared the whole manuscript and carried it 

 through the press. To Mr. Curtis's interest, and to his special experi- 

 ence as a meteorologist, the present volume is therefore largely due. 



Prof. Libbey has contributed Tables 38, 39, 55, 56, 61, 74, 77, 89, 

 and 90, and has also read the proof-sheets of the entire work. 



I desire to express my acknowledgments to Prof. Cleveland Abbe, 

 for the manuscript of Tables 32, 81, 82, 83, 84, 85, 86; to Mr. H. A. 

 Hazen, for Tables 49, 50, 94, 95, 96, which have been taken from his 

 Hand-book of Meteorological Tables ; and also to the Superintendent of 

 the United States Coast and Geodetic Survey, the Chief Signal Officer 

 of the Army, and the Chief of the Weather Bureau, for much valuable 

 counsel during the progress of the work. 



S. P. LANGLEY, 



Secretary. 



