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PIONEERS OF SCIENCE IN AMERICA. 



State of Pennsylvania." Mrs. Morehead quotes from the ac- 

 count of a friend who visited him in Philadelphia a description 

 of Prof. Espy's method of pursuing his atmospheric calcula- 

 tions, which necessarily had to be carried on out of doors. The 

 high fence inclosing the small yard was of smooth plank, paint- 

 ed white, while the space inclosed was filled with vessels of 

 water and numerous thermometers for determining the dew- 

 point. The white fence, when last seen by the narrator, was 

 so covered with figures and calculations that not a spot re- 

 mained for another sum or column. Prof. Espy's theory of 

 storms was first developed in successive memoirs in the Jour- 

 nal of the Franklin Institute, containing discussions of the 

 changes of temperature, pressure, and moisture of the air, and 

 of the direction and force of the wind, and other phenomena 

 attending remarkable storms in the United States and on the 

 ocean adjacent to the Atlantic and Gulf coast. "Assuming 

 great simplicity," says Prof. Bache, " as it was developed, and 

 founded on the established laws of physics, and upon ingenious 

 and well-directed experiments, this theory drew general atten- 

 tion to itself, especially in the United States. A memoir sub- 

 mitted anonymously to the American Philosophical Society of 

 Philadelphia gained for Mr. Espy the award of the Magellanic 

 premium in the year 1836, after a discussion remarkable for 

 ingenuity and closeness in its progress, and for the almost per- 

 fect unanimity of its result." 



In 1840 Prof. Espy, by invitation, visited England for the 

 purpose of explaining his theory of storms before the British 

 Association. He presented it, in an elaborate paper, in Sep- 

 tember, 1840, Prof. Forbes being the presiding officer of the 

 meeting, after which it was subjected to a lively discussion, in 

 which some of the most eminent British scientific men of the 

 day took part, some sustaining it and some presenting objec- 

 tions to it. He afterward visited Paris, and presented a com- 

 munication to the Academy of Sciences. The committee to 

 whom the communication was referred, consisting of MM. 

 Arago, Pouillet, and Babinet, at the conclusion of their report, 

 admitted that the memoir " contains a great number of well- 

 observed and well-described facts. His theory in the present 

 state of science alone accounts for the phenomena, and when 

 completed, as Mr. Espy intends, by the study of the action of 

 electricity when it intervenes, will leave nothing to be desired. 



