( 3°P > 
from hence, appear’d more elevated, by above 30 Mi- 
nutes, than it had done in the Beginning of September 
about Noon, on a very clear Day. From whence it 
appears, that the Refradion is at fome times greater than 
at others *, but probably *tis always very conhderable, 
and, as there is no certain Rule to make Allowance for it, 
it feems likely, that all Obfervations made on very high 
Hills,efpecially when view’d at aDiflance,and under finall 
Angles, as they commonly are, are uncertain, andfcarce 
to be depended on, generally erring in making the 
Heights greater than they really are. 
I then proceeded to obferve, as near as I was able, the 
Alteration of the Mercury in fome fmaller perpendi- 
cular Elevations, which we cou’d meafure with a Line, 
and alfo on the Tops of fome Hills of a moderate 
Height, whofe Altitude we cou’d obferve mofl commo- 
dioufty, and, by taking the Angles large, avoid the 
Danger of any confiderable Refradion. 
At the Bottom of the Tower of Halifax Church, the 
Mercury flood at 29 Inch. 78 *Dec. At the Top it fub- 
fided to 29. 66 . The Height of the Place, where the 
Obfervation was made, was found to be 102 Feet. 
At the Bottom of a Coal-Mine, near this Place, the 
Mercury flood at 29. 48. At the Top, it fell to 29. 32. 
The Depth of the Mine, being meafured, was found to 
be 140 Feet. 
At the Bottom of another Mine, the Mercury was ob- 
ferved to Hand at 29. yo. At the Top, it fell to 29. 23. 
The Depth of this Mine was 23 6 Feet. 
At the Foot of a fmall Hill, whofe Height we cou’d 
meafure very exadly, the Mercury flood at 29.81. At 
the Top it fell to 29. 45'. The Height of the Hill was 
312 Feet. 
At the Bottom of Halifax Hill, commonly call’d 
the Bank, the Mercury was obferved to Hand at 30. 00. 
Vol.XXXIH. Xx At 
