434 On the Effects of Heat and Moisture on Vegetation. 



We of the Carse of Gowrie, who live nearly half a degree 

 north from Edinburgh, are seldom blest with what Mr. 

 Playfair calls a good vegetating season, and yet vegetation 

 here is as forward as in the vicinity of Edinburgh, a proof 

 that its progress is not dependant solely on temperature. 



Before I had seen Mr. Playf air's method of division in keep- 

 ing a meteorological register, I divided each calendar month 

 into four parts, of seven days in each of the three first, and 

 nine or ten days in the last, according to the number of days 

 in the month, recording the mean temperature and depth of 

 rain in each division. The annexed diagram plate will at 

 one view show these results for Mr. Playfair's vegetating 

 season during the years 1823, 1824, and 1825. The blue 

 coloured line in the thermometrical index, shows the tem- 

 perature in 1823, the yellow in 1824, the red in 1825; simi- 

 larly coloured lines on the index of the Rain-guage represent 

 the depth of rain for the same periods. 



The variation in the different lines on the diagram point 

 out in a striking manner the variable nature of our northern 

 climate. The mean temperature, for the vegetating season 

 in 1823, was 50° 1' (for the whole of that year 45° 6'). The 

 rain that fell during the vegetating season amounted to 21£ 

 inches (during the whole of that year to 35.99 inches) the 

 average annual fall at this place being 27 inches. The pro- 

 gress of vegetation was unusually slow ; the low temperature, 

 the excessive quantity of moisture, and the want of sunshine, 

 retarded the ripening process of fruits, at least three weeks 

 beyond the usual period, and tender fruits on walls did not 

 ripen at all, nor was the wood ripened, as was shewn by the 

 scanty appearance of blossom in the succeeding spring. 



