PREFACE. 



Fifty years ago, when a tutor in Yale College, I became greatly interested in Redfield's inves- 

 tigations resjjecting tlie laws of storms; and from that time to the present day I have uever lost 

 luy interest in meteorological phenomena. In 183G I was appointed jmifessor of natural philos- 

 ophy in Western Reserve College, and was sent to Europe to purchase instruments for my 

 ilepartment. Among my purchases was a superior set of meteorological instruments, and on my 

 settlement in Ohio I commenced a meteorological journal, embracing daily observations of the 

 barometer, thermometer, &c., and I also made hourly observations for thirty-six hours at the equi- 

 noxes and solstices, according to the scheme proposed by Sir John tierschel. In October, 1837, a 

 hurricane of considerable violence passed within 5 miles of Hudson, and I improved the opportu- 

 nity to malie a careful survey of its track, with special reference to deciding between the conflict- 

 ing views of Kedtield and Espy, but the materials for this purpose were not as complete as I had 

 expected. In order to obtain fuller materials for this purpose I resolved to select some storm of 

 unusnal violence and collect all the information possible respecting it, and to make a thorough 

 examination of its phenomeua. I selected the storm of December 20, 1836, and succeeded in 

 obtaining a consideiable mass of observations relating to it. The results of this investigation 

 were published in the Transactions of the American Philosophical Society, and seemed to show 

 that neither the views of Redfield nor Espy were wholly correct, and that much remained to be 

 learned respecting the laws of our winter storms. I found it impossible to obtain observations 

 respecting the storm of December, 1836, which would enable me to make so complete an investiga- 

 tion as I desired, and I waited in the hope of being more successful with some future storm. 



In February, 1842, a tornado of unusual violence passed within 20 miles of Hudson. As soon 

 as I received tlie news, I started out with chain and compass to make a thorough survey of the 

 track, and succeeded to my entire satisfaction. As the tornado passed over a forest of heavy 

 timber, I had the best opportunity to learn the direction of the wind from the prostrate trees; 

 and by measuring the direction of the trees as they lay piled one upon another, I determined 

 the successive changes in the direction of the wind. The facts demonstrated incontestably that 

 the movement of the wind was spirally inward and upward, circulating from right to left about the 

 center of the tornado. This tornado was but an incident in a great storm which swept over the 

 United States, and I resolved to collect all the information possible respecting the general storm. 

 In this attempt I met with fair success, and in discussing the observations I adopted methods 

 which are now familiar to all the world, but which were new to me, and which, so far as I know, 

 had not at that time been employed by any other person. The results were published in the 

 Transactions of the American Philosophical Society. This investigation showed conclusively that 

 Eedfield was mistaken in supposing that in all great storms the wind revolves in circles about the 

 center ; and also that Espy was mistaken in supposing that the air moves toward the center in the 

 direction of radii. 



After completing this investigation, I desired to apply my new methods of research to another 

 violent storm, but the labor and expense involved in collecting my materials induced me to wait, 

 hoping that as the number of observers increased more abundant materials might be obtained, and 

 with a less expenditure of time andmoney. In 18.56, during a somewhat extended tour through 

 Europe, I improved the o])portunity to collect observations respecting a storm which prevailed in 

 Europe soon after ihe American storm of December, 1836, and which some persons supposed to 

 have been connected with the American storm. Qn my return to the United States these observa- 

 tions were carefully discussed and the results were published by the Smithsonian Institution. 



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