ADVERTISEMENT. 



IN connection with the system of meteorological observations established by 

 the Smithsonian Institution about 1850, a series of meteorological tables was 

 compiled by Dr. Arnold Guyot, at the request of Secretary Henry, and was pub- 

 lished in 1852. A second edition was issued in 1857, and a third edition, with 

 further amendments, in 1859. Though primarily designed for meteorological 

 observers reporting to the Smithsonian Institution, the tables were so widely 

 used by physicists that, after twenty-five years of valuable service, the work was 

 again revised and a fourth edition was published in 1884. In a few years the 

 demand for the tables exhausted the edition, and it appeared to me desirable to 

 recast the work entirely, rather than to undertake its revision again. After care- 

 ful consideration I decided to publish a new work in three parts Meteorologi- 

 cal Tables, Geographical Tables, and Physical Tables each representative of 

 the latest knowledge in its field, and independent of the others, but the three 

 forming a homogeneous series. Although thus historically related to Dr. Guyot's 

 Tables, the present work is so entirely changed with respect to material, arrange- 

 ment, and presentation that it is not a fifth edition of the older tables, but essen- 

 tially a new publication. 



The first volume of the new series of Smithsonian Tables (the Meteorological 

 Tables) appeared in 1893, and so great has been the demand for it that a second 

 edition has already become necessary. The second volume of the series (the 

 Geographical Tables), prepared by Prof. R. S. Woodward, was published in 1894. 

 The present volume (the Physical Tables), forming the third of the series, has 

 been prepared by Prof. Thomas Gray, of the Rose Polytechnic Institute, Terre 

 Haute, Indiana, who has given to the work the results of a wide experience. 



S. P. LANGLEY, Secretary. 



