143 



fore it is evident that in the greater part of England an error of 50 feet in 

 the height above sea, involves an error in the amount of rain indicated of 

 (30in. -^ 100 X 1-25 = 0-38) about four-tenths of an inch." 



I had made various attempts to ascertain the height of our city above sea- 

 level by means of simultaneous barometrical observations, and had come to the 

 conclusion that my garden was 184 feet above the half -tide Ordnance mark at 

 Liverpool, when it occurred to me to write to T. D. Roberts, Esq., C.E., at 

 Brecon, and ask the difference of level between J^Ioorhampton station on the 

 Brecon line and the Barton station at Hereford, intending afterwards to find the 

 difference of level between Moorhampton station and AVeobley, as the Ordnance 

 line of levels passes through the latter place and there is a first-class bench mark 

 (bolt) on the church wall. But Mr. Eoberts has kindly saved me all further 

 trouble ; for he joined the levels of the Brecon line with those of the Ordnance 

 survey at Hay, and then made out and sent me the altitudes of all the stations 

 from Hay to Hereford, thus furnishing us with what has been so long a desidera- 

 tum to the scientific men of Hereford, viz. , the height of the city above the sea as 

 demonstrated by actual levelling. According to Mr. Roberts the Moorfield 

 station is 179 feet above the sea, and my garden 182 feet. 



Mr. Roberts's altitudes are as follows : — 



FT. 



Levels of rails at Hay 254'12 



Whitney Station 259 "78 



Eardisley 230-12 



Moorhampton 33717 



Credenhill 2.51-62 



MoorfieWs 179-12 



Barton 175.77 



Rails on Bridge over Canal at "Widemarsli ... 183-98 



As the subject is one of importance to rainfall observers, I subjoin a few 

 altitudes taken from the Ordnance Map and 



THE ABSTRACT OF SPIRIT LEVELLING. 



FT. 



GarwayHill 1197-0 



Worcester Beacon ... ... 1395'0 



May Hill 9730 



^ r Eardisley Church 2.55-884 (bolt)* 



% 1 Weobley Church 316-300 (bolt) 



S J Leominster : 



-a 1 Dishley Street 264-355 (bolt) 



g I Town Hall 2.50-478 (bolt) 



(2 LLeintwardine Church ... ... 440-035 (bolt) 



By means of two aneroids, reading exactly alike, the altitude of any place 

 ■within the distance of three miles from any one of the points named may be 

 taken with sufficient accuracy for rainfall obser\'ations. 



Mr. Symons gives the following directions :— " If the bench mark and the 

 gauge are not more than two mUes apart, and their difference of altitude is 



* The bolt mark is a kind of first class mark ; a bolt of copper beiog driven into the 

 stone instead of a mere mark cut upon it. 



