276 Mr. J. Glaishel' 07i the Meteorology of England. 



It is desirable to compare the results deduced by means of 

 the preceding formulae with the observed results, not only 

 for the purpose of testifying their accuracy, but also to examine 

 the accuracy of the several instruments which have been used 

 at the different stations. 



The annexed table shows the results of this comparison. 



In viewing the differences shown in the fourth and tenth co- 

 lumns between the observed and calculated pressures, it is evi- 

 dent that at most places the instruments are good. When we 

 view the diff'erences which some of the places present, we shall 

 readily see that the instruments at those places need correction. 

 The barometer at Exeter seems to read too low by 0"103 inch ; 

 that at Uckfield to read too high by 0*131 inch ; and that at 

 Derby to read too low by 0*193 inch. These corrections 

 should be applied to the readings of these instruments till the 

 true values are determined by a direct comparison with a 

 standard. 



I proceed to consider the numbers in the thirteenth column, 

 showing the differences between the observed and calculated 

 annual temperatures of the air. These differences are generally 

 small, and quite within the probable errors of the instruments 

 themselves. This formula therefore may be considered to give 

 the true temperature ; and from it the mean temperature of 

 any place in England may be calculated for the year 1847. 

 The differences at Brighton and at Beckington are large, and 

 the annual temperatures as determined at those places are 

 either erroneous, or those places are subjected to a peculiar 

 local influence. Let us turn for a moment to the annual tem- 

 perature as determined from the corrected readings of the dry 

 bulb thermometer in the yearly table at both these places. 

 Theannual temperatures, as thus deduced, are nearer the com- 

 puted values than those determined from the maximum and 

 minimum thermometers ; and it would seem that the self- 

 registering instruments are in error, and that the differences 

 are not due to local disturbances. At Derby and at Notting- 

 ham the instruments require correction. At Liverpool the 

 difference shown would seem to be due to locality. 



The differences in the thirteenth column, at those places 

 situated in the counties of Cornwall and Devonshire, are small ; 

 therefore the annual temperatures of these places are only those 

 due to their latitude. In turning our attention to the 16th, 

 19th, and 22nd columns, we at once perceive the cause of the 

 loveliness of the climate of those counties to be the uniformity 

 of their temperature. Their yearly, monthly, and daily ranges 

 are respectively 28°, 15°, and 7^ less than those due to their 

 latitude. 



