1890.] The Modern Weather Bureau. 19 



when about 1833 he announced the latent heat evolved in the 

 condensation of vapour into cloud and rain is the sustaining power of 

 the storm. We owe to Espy the practical introduction in 1830 of the 

 whirled Psychrometer, a table for use with it for obtaining dew 

 points, the determination of approximate rate of cooling of ascending 

 air, the correct explanation of the diurnal period in the velocity of the 

 wind and a series of daily weather maps for the United States based 

 on an hundred stations for over 15 years (with occasional gaps) ; a 

 selection from these maps is published in his reports, and the whole 

 work led him to a long series of generalizations as to the movements 

 of storms over the United States. In this latter work he was the 

 pioneer of the world, and to the present day no one man has, so far as I 

 know, accomplished any greater work in meteorology. I wish I could 

 stop to tell you more about him, for he was personally one of the most 

 interesting figures in the annals of science. His ancestors were 

 Huguenots who had fled to Northern Ireland and thence emigrated 

 to Lancaster County, Pennsylvania, where their descendants held 

 distinguished positions in public and private life ; he was himself 

 thoroughly educated in the languages and law ; he received his title 

 " professor " from being at the head of well-known academies ; first in 

 Cumberland, Maryland, afterwards in Philadelphia. Very early in 

 life his attention was drawn to the study of storms, and from 1817 to 

 1857 he observed, studied, wrote, and lectured everywhere on this 

 subject. Being so far in advance of his time it was natural that the 

 community should seize upon and exaggerate some features of the 

 views maintained by him ; but his soubriquet, " The Storm King, "" 

 correctly pictures the impression he made upon all his hearers. His- 

 enthusiasm was intense and led him to talk, write, and lecture upon 

 his views whenever occasion offered, hoping thereby the sooner to 

 convince his fellow-citizens that storms and weather can be predicted. 

 In 1847 Prof. Joseph Henry, in his first report as Secretary of the 

 Smithsonian Institution, publicly came to the support of Espy, with 

 whom he had for ten years had frequent intercourse in Philadelphia 

 and Princeton. In 1849 Henry obtained from the Electro-Magnetic 

 Companies the privilege of receiving at Washington daily weather- 

 telegrams free of expense, the same to be used for the purpose of 

 studying storms and of demonstrating to the members of Congress that 

 the weather can be predicted from day to day. This gratuitous- 

 assistance was rendered by the telegraph companies all the more 

 readily because it was well recognised that the electro-magnetic 

 telegraph, as it then existed, would not have been possible but for the 

 discoveries in electric science made just previously by Prof. Henry,, 

 in his laboratory in Princeton, and which had been utilized by Morse 



and his assistants. Henry's interests in meteorology now came to be 

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