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the centre of the storm; but when the winds are moderate, which is the case 

 of most frequent occurrence, this tendency is very fully developed, and 

 the subject demands more particular investigation. 



III. I now proceed to inquire what encouragement there is to a further 

 prosecution of meteorological researches. 



In all our investigations respecting natural plienomena we assume that 

 the operations of nature are subject to laws, and that these laws are uni- 

 form in their operation. A law of nature knows no exceptions. There 

 is no place for science except upon this basis. Are storms subject to laws, 

 and are these laws invariable? Such a question may appear almost like 

 trifling, and yet many argue as if they had but feeble faith in these princi- 

 ples. It is presumed that no philosopher will seriously question them; but 

 it may be said that these laws are so complex that they can never be dis- 

 covered. What right have we to make such an assumption? Have not 

 the laws of nature been actually discovered in many cases in which they 

 appear equally complex? How long is it since comets were believed 

 to rush through the planetary system in defiance of all law; or if subject 

 to law, then a law of such complexity that all attempt to discover it seemed 

 hopeless? Now, these laws appear so simple that we wonder they were 

 not sooner discovered. All the laws of nature appear complex while they 

 remain unknown; but when once discovered, we are surprised at their sim- 

 plicity. Why should storms form an exception to this rule? Does the 

 past history of meteorological investigations justify such a conclusion? 

 Have our researches been rewarded with no success? Far otherwise. 

 During the brief period that meteorology has been cultivated we have ar- 

 rived at many important generalizations, which, if notentided to the name 

 of laws of nature, atford the strongest assurance that such laws exist, and 

 that we are on the eve of their discovery. We have discovered that the great 

 storms of the United States travel nearly from west to east. No instance 

 has yet been found in which a violent storm in these latitudes has travelled 

 from east to west, although some great rain storms have remained nearly 

 stationary for a day or two. Violent storms usually travel at the rate of 

 about 25 miles per hour, although this velocity has been observed to rise 

 as high as 40 miles. These storms are of various dimensions. While 

 summer showers may cover an area of but a few miles, winter storms some- 

 times have a diameter of 1,000 miles and upwards. The duration of a 

 storm at any place depends upon its extent, and upon the velocity of its 

 progress. If the diameter of a storm is 500 miles, and its progress 25 

 miles per hour, its duration at a place situated in the centre of the track 

 will be 20 hours, and less for places out of the centre. Hence we may 

 form some estimate of the superficial extent of a storm from its duration at 

 any place. The direction of the wind is generally inward towards the 

 area of rain, and in violent storms there is a tendency to rotation about a 

 vertical axis. Over a rugged country there are so many obstacles to the 

 wind's progress, that observations at the surface of the earth present a great 

 many anomalies; but at sea there are no such obstacles, and the observa- 

 tions of the wind exiiibit a greater uniformity and simplicity. The ba- 

 rometer falls under the first half of the storm, and rises as the storm re- 

 cedes; the centre of the storm coinciding nearly with the greatest depres- 

 sion of the barometer. The passage of this centre is marked by a sudden 

 change of wind to a point of the compass nearly opposite to that from 

 which it had previously been blowing. 



