[23] 



208 



adopted twelve years ago of investigating the phases of storms, by the joint 

 committee of the American Philosophical Society and the Franklin Insti- 

 tute, of the State of Pennsylvania. 



The plan then suggested, and in part carried out, was adopted in the 

 investigation of the phases of storms during tlie five years in which I was 

 in the service of the government. In my "circular to the friends of 

 science," in which I invited all persons in the United States keeping 

 journals of the weather to send them to the office of the Surgeon General, 

 Washington, 1 announced my intention to lay down on skeleton maps of 

 the United States, by appropriate symbols, all the most important phases 

 of great storms which might come within the range of our simultaneous 

 observations ; and thus it was hoped we should be able to determine the 

 sJiape and size of all storms; whether they are i^ound or oblong; and if ob- 

 long, whether they move sideforeinost or eiidforemost , or ohliquehj; and to 

 ascertain their velocity and direction in all the different seasons of the 

 year; the course of the wind in and beyond the bordere of the storm; the 

 Jluctuacioii of the barometer and change of temperature which generally 

 accompany storms, and the extent to which their influence is felt beyond 

 their borders. 



Having obtained observations from a wide extended correspondence, I 

 laid down the phases of the storms on maps, as presented in my first re- 

 port, and I have continued the same plan in my second report, now ready 

 to be printed. In the investigation of the materials of the second report, 

 comprising tlie observations of three years and three-quarters, I have dis- 

 covered no facts contradictory to the generalizations deduced from the 

 winter storms of three months embraced in the second report. I consider 

 it of the highest interest, by an extended series of observations, which I 

 hope the Smithsonian Institution will cause to be made over a much wider 

 territory than my observation embraced, to verify, or, if necessary, modify 

 these generalizations, and also to investigate the laws of summer storms, 

 which 1 fear cannot be done without much more numerous observers than 

 I was able to procure.* 



''[*■ ^ ^ ^ ^F W vr ^ 



The elements of the theory I have given you are the same as those pre- 

 sented in my work on storms; and though I have demonstrated thetn ap- 

 proximately, and have no doubt of their general accuracy, yet I am con- 

 vinced that nothing will establish the truth on this subject in such a man- 

 ner as to carry conviction to every mind but a series of wide extended 

 simultaneous observations, continued for a long time, by numerous observ- 

 ers. Such a series I hope is now about to be made. 



It would be inappropriate to extend this communication to a greater 

 length; but I will explain to you at another time some experiments con- 

 nected with meteorology, which I wish to see performed, on the electricity 

 of steam, and on the specific caloric of atmospheric air and other gases, 

 with the aid of my nephelescope, and on the law of cooling of air in great 

 expansions of air by diminished pressure. 



I remain, very respectfully, yours, &c., 



JAMES P. ESPY. 



Prof. J. Henry, 



Secretary SndtJisonian Institution. 



*Tlie generalizations and theory of Mr. Espy are given in the preceding report oi" Professor 

 Loomis, page 197. 



