97 



The Woolhope standard is now at Kew, and we can do nothing until it 

 has been returned to us with a character ; but it will be well to continue these 

 observations as occasion may offer, both because we shall thus obtain a very close 

 approximation to the exact heights of all the hills in tlie neighbourhood of 

 Hereford, and also because the proving of our work by levelling, which sooner 

 or later wiU doubtless be done, will enable all who are interested in the question 

 to form a judgment respecting the value of the barometer as an insti-ument 

 for measuring altitudes. 



The aneroid has been used by us in conjunction with the mercurial 

 barometer whenever Mr. Cooke has taken part in our proceedings, and we are 

 weU convinced that its value as a substitute for the latter is very great. In our 

 work we have used an aneroid by Negretti and Zambra ; it belongs to Mr. 

 Cooke, and its performance is excellent. Dr. Balfour Stewart, Superintendent 

 of Kew Observatory, and, of course, a very high authority on all such points, 

 speaks highly of the accuracy of the aneroid when applied to the measurements 

 of heights. He has, I believe, suggested a method for the correction of a 

 certain amount of error which the instrument is liable to when taken up very 

 high mountains. Correction for temperatm-e (for the aneroid) is stUl a question. 



Fui'ther trials of this kind are very desirable ; the portability of the 

 aneroid making it a most valuable instrument even now; but an instniment 

 absolutely perfect, if a table of corrections could be made out rendering it possible 

 to compare its readings accurately with those of a standard barometer. 



The mean temperature for 1867 was 48'33, as shown by the thermometers 

 placed in my garden. According to the Blue School thermometers it was 48"45. 



Mr. Glaisher has determined the average yearly temperature at Greenwich 

 to be 49 and a very small fraction. "We were therefore a little below the average 

 in 1867, but the temperatiu-e was occasionally very high. The table (2) shows 

 high thermometer readings in May, June, July, and August. In the last named 

 month the thermometer in shade rose on one occasion to 80 '6. 



The lowest temperature occiu-red on the 5th of January, when the 

 thermometer went down to 8 "5. 



The monthly means, as shown by the thermometer at the Blue School, 

 came very near those calculated from the day and nigJit readings of the 

 instniment in my garden. The latter will be found in the table (2), the former 

 are as f olio ws : —January, 34-2; February, 45-19; March, 36 '67; April, 49-34; 

 May, 52-82 ; June, 57-91 ; July, 59-44 ; August, 61-18 ; September, 56-37 ; 

 October, 49-64; November, 39 '59; December 39-12. 



The thermometer-stand at the Blue-school is attached to the wall of the 

 school (a waU without door or window), and the instniments are in some measure 

 affected by the temperature of the building. They appear to be cooled during 

 the day, at least in warm weather, and warmed at night during cold seasons ; but 



