of an Arc of the Meridian. 
489 
CONCLUSION. 
From th‘s measurement it appears, that the length of a 
degree on the meridan, in latitude 52 0 2' 20", is 60820 fathoms. 
This conclusion is deduced from the supposition of the whole 
arc subtending an angle of 2 0 50' 23", 38 in the heavens, and a 
distance of 1036337 feet on the surface of the earth. 
The length of the degree at the middle point (51° 35' 18") 
between the southern extremity of the arc and Arbury Hill, is 
60864 fathoms ; which is greater than the above, and exceeds it 
by 44 fathoms. But this degree, admitting the earth to be an 
ellipsoid, with the ratio of its axes as 229 to 230, should be 
about 10 fathoms less. If the measurement of the terrestrial 
arc be sufficiently correct, and the earth of an elliptical form 
in these latitudes, either the arcs affording the deductions are 
incorrect, or some material deflection of the plumb-line has taken 
place, at one or two stations, from the effect of attraction. 
Without arrogating to myself any merit from the pains taken 
in the performance of this undertaking, I may say, I am so 
perfectly convinced of the general accuracy of the whole, that I 
cannot for a moment doubt the collective evidence of its suffi- 
ciency. From an examination of my field books, and from the 
remeasurement of the chains used in our base-line on Misterton 
Carr, I think it is probable that an error in the whole distance, of 
197 miles nearly, does not subsist to an amount of more than 
100 feet, corresponding to 1" in the amplitude of the whole arc; 
and I also think it probable it cannot amount to halt that 
quantity. The supposition of the zenith distances of the stars 
being generally erroneous, at any one station, cannot be ad- 
mitted, unless it should be imagined, tnat the plane of the 
