218 A COMPARISON BETWEEN THE 



In June the maximum of the barometer in London (cor- 

 rected as before stated) was 30.^25, the minimum 29.597 > 

 the mean 29.930 j the range .728. In Malvern the maxi- 

 mum was 29.746, the minimum 28.953 j the mean 29.332, 

 and the range .793. 



In July the maximum height of the barometer in London 

 ■was 30.2*13, the minimum 29.396 ; the mean 29.876, and 

 the range .817. In Malvern the maximum 29.665, the 

 minimum 28.892 ; the mean 29.269 j the range .773. 



In August the maximum in London 30.109, the mini- 

 mum 29.593 5 the mean 29.819, and the range .516. In 

 Malvern the maximum 29.572, the minimum 28.955 ; the 

 mean 29.245 j the range .617. 



From this we obtain for the summer quarter — 



Mean Height. Mean Range. 



London 29.875 687 



Malvern 29.282 727 



The height of the Worcestershire Beacon is stated, on the 

 authority of Col. Mudge, to be 1444 feet above the mean level of 

 the sea ; and from an apparently careful and correct barometrical 

 measurement (the details of which will be found in the first volume 

 of " The Analyst") it appears that the height of the Beacon above the 

 village of Great Malvern is 924 feet ; these statements therefore 

 leave 520 feet as the elevation of Malvern : and for this it becomes 

 necessary to add .570 to all the barometrical heights observed 

 there. If the reader should take the trouble of doing this to any 

 of them, he would then immediately perceive the very slight 

 differences in the fluctuations of the barometer in London and 

 Malvern. 



In looking over the various daily details from which the fore- 

 going mean barometrical heights have been deduced, the coinci- 

 dence in the movements of the two barometers was so constant, 

 that we have taken pains to determine accurately this point j and 

 upon comparing the daily fluctuations, for a whole month, at the 

 same time at each i)lace, after every necessary correction, the 

 variation between the simultaneous movements of each has never 

 amounted to so much as ' inch, very generally not more than a 



few hundredths, a result peculiarly establishing the constant mag- 

 nitude of the atmospheric movements. 



There are many minor circumstances likely to introduce discre- 

 pancies in any comparison between the heights of two barometers 



necessary that the elasticity of the vapour of the atmosphere should be estimated at 

 each place, by determining the dew-point, and adding or subtracting according as it 

 is higher or lower in the one place or the other. — This would be a very laborious 

 task ; and as the correction is always small, it has been neglected. I have made 

 the correction for the means of the different seasons hereafter stated, and I find the 

 difference between the barometer in London and Malvern to be, for the summer 

 quarter, only X)07 in., and for the autumn .016 in. 



