446 WRITINGS OF JOSEPH HENRY. [1865 



SYSTEMATIC METEOROLOGY IN THE UNITED STATES. 

 (From the Smithsonian Annual Report for 1865, pp. 50-59.) 



It has been aptly said that man is a meteorologist by 

 nature. He is placed in such a state of dependence upon 

 the atmospheric elements, that to watch their vicissitudes 

 and to endeavor to anticipate their changes become objects of 

 paramount importance. Indeed the interest in this subject 

 is so absolute that the common salutation among civilized 

 nations is a meteorological wish, and the first introduction to 

 conversation among stangers is a meteorological remark. Yet 

 there is no circumstance which is remembered with so little 

 exactness as the previous condition of the weather, even from 

 week to week. In order that its fluctuations may be preserved 

 as facts of experience, it is necessary that they should be con- 

 tinuously and accurately registered. Again, there is perhaps 

 no branch of science relative to which so many observations 

 have been made and so many records accumulated, and yet 

 from which so few general principles have been deduced. 

 This has arisen, first, from the real complexity of the phe- 

 nomena, or in other words from the number of separate 

 causes influencing the production of the ordinary results ; 

 second, from the improper methods which have been pur- 

 sued in the investigation of the subject, and the amount of 

 labor required in the reduction and discussion of the obser- 

 vations. Although the primary causes of the change of the 

 weather are on the one hand, the alternating inclination of 

 the surface of the earth to the rays of the sun, by which its 

 different parts are unequally heated in summer and in 

 winter, and on the other, the moisture which is elevated 

 from the ocean in the warmer and precipitated upon the 

 colder portions of the globe ; yet the effects of these are so 

 modified by the revolution of the earth on its axis, the con- 

 dition and character of the different portions of its surface, 

 and the topography of each country, that to strictly calcu- 

 late the perturbations or predict the results of the simple 

 laws of atmospheric equilibrium with that precision which 



