32 ' 



HATTKRAL HILL. 



August 3rd, 1870. — A careful reading was taken at the Pandy station, 

 345 feet above sea-level by levelling, and another on the top of that portion 

 of the Herefordshire Black Mountain which is marked Hatteral Hill on the Ord- 

 nance map, as soon as the summit could be reached. 



On the return to Pandy a second observation was made, and the mean of the 

 two lower readings taken and found to be 29 434 inches, corrected. 



The reading on the top of the mountain, corrected, was 28 '032 inches. The 

 difference between the higher reading and the mean of the two lower ones was 

 1*402 inch, the mean temperature 73", and the deduced height, calculated by 

 means of Negretti's tables, 13S6"5 feet. If to this measurement we add the height 

 of the Pandy station above the sea we shall make the full height of Hatteral Hill 

 1,731 feet 6 inches. 



At the same time that I made my barometric observation on the top of Hatteral 

 Hill my daughter made another at Hereford, and the difference between the two 

 barometers was found to be equal to 1.570 '9 feet in perpendicular height. Add to 

 this 187 feet, the height of my barometer above the sea, and the altitude of the 

 mountain above sea-level will be 1,758 feet or nearly so. 



At first sight a difference of 26 feet may appear very great, but the distance 

 between the barometers — 15h miles — was also very great (far too great in fact for 

 accuracy, one observation only being taken), and yet even at that distance a pretty 

 close approximation to the actual height of the mountain was evidently gained, 

 and the mean of half a dozen observations would probably have given the height 

 to a foot. 



GAEWAY HILL. 



Garway TTill was measured a second time on October 2, 1868. The day was calm 

 and everything most favourable. Three barometric readings were taken simul- 

 taneously at intervals of half an hour each, both on Garway and at Hereford. 



The mean of the three barometric readings at Hereford was 29 '928 inches 

 corrected ; and the mean of the three readings of the detached thermometer 50'7. 



The mean of the three barometric readings taken on Garway was 28 '832 inches, 

 corrected, and the mean of the three readings of the detached thermometer 47° '0. 



The barometric difference between Hereford and Garway was 1"096 inch, and 

 the mean temperature (Hereford and Garway) 48°-8. This, allowing for height of 

 barometers from the ground, showed an altitude of 1,013 feet 10 inches ; or, in 

 round numbers, 1,014 feet. Add to this 182 feet, the height of Kichmond-place 

 above the sea, and we have 1196 feet, for the height of our mountain. The 

 Ordnance Survey determines it to be 1,197 feet. As the barometers were lOJ 

 miles apart this was a most satisfactory instance of barometric measurement. 



LADT-LIFT. 



The mean of two measurements (February 5th and July 19th, 1869) is V39 

 feet above Hereford and 921 feet above sea-level. The distance, however, from 

 Hereford is 9.^ miles in a straight line, so that it would be satisfactory to make 

 ■erne more measurements and then takethe mean of the whole. 



