335 
Measurement of three Degrees of the Meridian. 
Clifton and Dunnose 
{ 2® 50' 23", 35 observed 
2 50 21 ,97 calculated 
Difference 
+ 1 > 3 ^ 
Clifton and Arbury 
1 1® 3 4' 3", 40 observed 
1 1 13 58 ,63 calculated 
Difference + 4 >77 
Arbury and Dunnose 
f i° 3b 7 19", 95 observed 
1 1 36 23 ,34 calculated 
Difference 
— 3 >39 
These differences are really considerable, and are capable 
of producing important errors in the results dependent on 
them. 
In the first place we see, that the southernmost arc between 
Dunnose and Arbury is smaller than it would appear by com- 
putation, by as much as 3", 4, and when this deficiency is 
combined with an excess of 8 toises in the linear dimensions 
of the same arc, it makes as much as 40 toises difference in 
the estimated length of a degree. The reverse of this occurs 
in the northern portion of the arc comprised between Clifton 
and Arbury Hill. This is larger than it ought to be by 4" ,77* 
and hence the value of a degree on the meridian turns out too 
small by about 6 2 toises in its linear dimensions. Fortunately, 
however, the excess of the total arc is extremely small, as it 
does not exceed i", 38, so as to make but 5 or 6 toises differ- 
ence in the length of a degree observed on the meridian, and 
corresponding to the mean latitude of the arc examined. 
X x 2 
