CLIMATOLOGY. 87 



Howard and Coneysthorpe both upon the arenaceous Inferior 

 Oohte at 250 feet and 200 feet respectively, and Kirkham 

 upon the Sandstone in the immediate vicinity of the Derwent 

 at 50 feet lower than Coneysthorpe. The fall of temperature 

 does not grow greater here as we ascend, but precisely the 

 contrary. In Scotland the average minimum for the stations 

 of the Meteorological Society in the low part of Aberdeenshire 

 was 6 degrees below zero, but at Braemar and Castle Newe, 

 in the upper portion of the county, it did not sink below 8 and 

 10. At Edinburgh the minimum was — 6, but at Wanlockhead 

 in Dumfriesshire, which is 1333 feet above the sea-level, it was 6. 

 We shall have to speak further about the distribution of winter 

 minima when we come to treat upon the topography of wild 

 and cultivated plants. 



Mean Temperatures in the Sun and upon the Ground. — The 

 foregoing tables, it will be observed, all relate to the tempera- 

 ture of the air in the shade. But, especially under an unclouded 

 sky in summer time, the direct action of the solar rays exerts a 

 powerful heating influence, so that the average daily maxima 

 of exposed places rise much higher than those which shaded 

 positions reach. And at night the minimum of the ground 

 is more or less below the minimum of the air. The following 

 tables for Bywell and AUenheads give month by month in the 

 first column the average excess of the daily maxima in the sun 

 above those registered in the shade, and in the second the 

 average fall of the nightly minima on the grass below those of 

 the air. In the third for each locality the average daily range 

 in the shade is given, and by adding to this the other two 

 numbers we obtain in the fourth column the extreme range of 

 the 24 hours, that is to say the average daily difference between 

 the lowest point to which a thermometer placed upon the 

 ground sinks down at night, and the highest point to which 

 one that is fully exposed to the sun's rays in the day-time rises 

 up. 



Juno 1888. 



