84 baker's north Yorkshire. 



kept at Bywell during exactly the same period as those at Allen- 

 heads give the mean annual temperature of that station at 48 "3, 

 a difference of 5*2 degrees for 1300 feet, which is exactly i 

 degree for 250 feet. Dr. Dalton long ago stated the diminu- 

 tion for the hills of the North of England at i degree for every 

 hundred yards of elevation, which for the air is probably not 

 far from correct, and furnishes a convenient figure for calcula- 

 tion. Of course the rate at which temperature decreases up- 

 wards will depend greatly upon exposition and other modifying 

 influences. A station in a sheltered dale will be much warmer 

 than one upon an exposed plateau at an equal elevation. 

 Temperature will decrease more rapidly upon an isolated peak 

 than where there is a greater mass of hill, and at a more rapid 

 rate, other things being equal, the higher we rise above the 

 level country. The hiberno-sestival difference at Allenheads 

 according to the preceding table is more like that of Scar- 

 borough than that of York. The difference between Allenheads 

 and York, which is 3'i upon the mean of the year, sinks to i"9 

 upon the average of the winter, rises to 4*3 in the spring, con- 

 tinues at 4'o during the summer, and sinks again to 2*2 in the 

 autumn ; and although two sets of observations brought into 

 comparison must of necessity yield very insufficient grounds 

 upon which to establish general conclusions, yet one would 

 suppose d priori, and it also seems likely from other considera- 

 tions, that the distribution of at any. rate the dale temperatures 

 throughout the seasons is after a manner intermediate between 

 that of the open low inland country and the sea-side, and 

 that like the sea-coast elevated masses of land cut off the 

 extremes of the year and postpone its warmth. And it is worthy 

 of notice also that the difference between the average daily 

 maxima of Allenheads and York is nearly i degree greater than 

 the difference between their average daily minima. 



We must take then the average temperature of the sea-side 

 at 47 or something over, with a hiberno-aestival difference of 

 17 or i8; of the low inland country at 46^ to 47/^, with a 



