42 



its cold, and another for its heat, is there no reason for it ? Is there not some 

 cause acting upon a grand scale to bring about this result? Is there no 

 cause which brings an excess of winds from the north, or an excess from 

 the south — which brings an unusual amount of precipitation, or an extra- 

 ordinary degree of cloudiness? And cannot this cause be discovered? 

 This discovery may require the exercise of patience — it may require a 

 long continued series of observations ; but to assume that a principle can- 

 not be discovered, is unphilosophical. This is a legitimate subject of in- 

 vestigation, and it is a field in which the laborer cannot fail of reaping his 

 reward. We only need adequate observations — observations sufficiently 

 precise, and upon a scale of proper extent. We conclude, then, that there 

 is the highest encouragement to the prosecution of meteorological inqui- 

 ries — that by continuing our researches we may hope to arrive at general 

 laws, and that a knowledge of these laws cannot fail to contribute to the 

 wealth and happiness of mankind. 

 I proceed, therefore, to inquire — 



IV. Upon what plan the observations should be conducted to secure the 

 object proposed. 



Violent winter storms appear most suitable for investigation, because 

 they are of longer duration, and their features are more strongly marked. 

 The oscillation of the barometer affords the surest criterion for identifying 

 a storm in its progress from day to day; and these oscillations are greatest 

 in winter. 



1. How large an area should be covered by our observations, to enable 

 us to investigate advantageously the phenomena of our winter storms? 



Our observations ought plainly to embrace the entire region of the 

 storm, and even extend somewhat beyond its margin, for in no other way 

 could we be sure that we had found its limits. Now, the great storms 

 which are experienced between the parallels of 40 "and 45 degrees are fre- 

 quently felt as far south as latitude 30'^, and sometimes to 25°, South of 

 this line, the oscillations of the barometer, except in a few rare instances, 

 are quite small; and it is probable that the limiting parallel of the trade 

 winds forms a dividing line between the ordinary storms of the torrid and 

 temperate zones. We should therefore extend our system of observations 

 to the southern margin of the United States. The northern limit of our 

 ordinary winter storms remains unknown. In the storm of December 21, 

 1836, the oscillation of the barometer increased uninterruptedly with the 

 latitude as far as the most northerly station, Quebec. Only the southern 

 half of the storm was included within the United States. This storm was 

 probably experienced as far northward as to the northern shore of Hudson's 

 bay. We should therefore extend our system of observations to the north- 



