Meteorological Ohservatiovs. 225 



peratiire exceeding 100^ of Fahrenheit; wiiereas, the real temper- 

 ature of the cHmate of the northern and middle states, seldom, if 

 ever, reaches 98°. Experience has shown that the mean temper- 

 ature of the day, is very nearly ascertained by taking the mean 

 of two observations, the one made at sun-rise, which is the cool- 

 est period, and the other at noon, or rather an hour or two after, 

 which is the warmest period. This plan will be adopted in find- 

 ing the monthly mean given in the following tables, or monthly 

 summaries. The observation taken in the evening, will, there- 

 fore, not be used in estimating the general average. 



In regard to the wdnds, I have deviated from the common 

 practice of classing them merely according to their direction, 

 choosing rather to arrange them with reference to their general 

 character. The first class, called Northerly, comprises such winds 

 as flow from between the W. N. W., and N. N. E. points of the 

 horizon, including those two points. They have always the same 

 general character, being dry, and in the winter, cold. The 

 second class, Easterly, embraces those which set in from N. E. to 

 S. S. E. inclusive, which are damp, and often rainy and attended 

 with storms. The other class, Southerly, consists of southerly and 

 westerly winds, always warm, and in the summer dry, but ac- 

 companied with rain in the winter. 



The number of clear days in a month, does not always repre- 

 sent the propoi;tion of clear weather in the same time ; for many 

 of the days not entirely clear, may have been partially so. 

 Hence I have added the proportion of clear weather in each month, 

 in which, such days as were partly clear have been regarded. — - 

 The remaining parts of the summary will explain themselves. 



In order to commence with the beginning of a season, the 

 month of June is first given, although the " Journal of Geology," 

 &c. was not commenced until the next month. The sixth num- 

 ber of the Ji^urnal will contain three summaries, concluding with 

 October, and each succeeding number will contain the summary 

 for the second month preceding its publication. At the close of 

 the year, a yearly summary will be furnished. 



Meteorological Summary, for June, 1831. 



Average at sun-rise, Thermom. 64°.20 Barom, 29.89 inches. 

 " at mid-day, 79°.67 29.84 " 



" at 10 P. M. 68°.60 29.84 " 



Vol. L— 29 



