4 PREFACE TO THE FIRST EDITION. 



In the selection of the matter, I have been guided by the idea that the 

 tables which I sought for my own use might also be those most likely to 

 be wanted by others. But I wish the following to be considered as a 

 first collection, containing only the tables most appropriate to the present 

 purpose. They are, therefore, arranged in different and independent series, 

 with distinct paging, but constituting together a frame- work into which 

 any tables may be readily inserted when wanted, either to make the collec- 

 tion more complete, or to present a choice of tables calculated from some- 

 what different elements, or adapted to various methods of calculation. 



The measurement of heights by means of the barometer being inti- 

 mately connected with Meteorology, it was thought not inappropriate to 

 admit into this collection Hypsometrical Tables, destined to render this kind 

 of calculations more easy and more rapid, and thus to increase the taste for 

 a method so useful in physical geography. I have preferred the tables of 

 Delcros, as uniting in the . greatest degree simplicity and accuracy. Those 

 of Gauss, Bessel, and Baily may be given afterwards. 



Every table contains directions for its use, when necessary ; moreover, 

 the indication of the elements used in its calculation, and of the source 

 from which it has been taken. When no remark is made as to this last 

 point, the table has been expressly calculated for this volume. 



Very respectfully, 



Your obedient servant, 



A. GUYOT. 



Cambridge, Mass., December 15th, 1851. 



