3«4 
An Account of the Measurement 
done, my reasons for selecting Dunnose as one of the extre- 
mities of my meridional line, and also those for preferring its 
meridian to any other; which I shall do as briefly as possible. 
In a country whose surface, throughout its whole extent, is 
equally diversified with hilly ground, that particular part of it 
should be chosen, for carrying on a meridional measurement, 
which comprehends the most extensive arc. This arises from the 
necessary consequence which attends an operation in a country 
so circumstanced ; as, possibly, no spot fixed on for a place of ob- 
servation, could be supposed free from the effects of the unequal 
attraction in the adjoining matter. In such a country, therefore, 
a measurement upon the most extensive arc, must give the 
most accurate conclusion ; for the errors arising from the cause 
here mentioned, like those of observation, lessen in their effects, 
on their application to arcs of increasing magnitude. 
If Great Britain were a country thus diversified, the most 
eligible part would be that where the meridian from Lyme, in 
Dorsetshire, passes northward into Scotland. The difference of 
latitude between that place and Aberdeen, near to which that 
line cuts its parallel, is 4 0 47', nearly. But, however great the 
advantages attending such a length of arc might be, under 
the general circumstances of accurate terrestrial measurement, 
and accurate observations at its extremities, no beneficial conse- 
quences could be expected to attend the placing of the sector at 
intermediate stations; as the arc would be found running,almost 
every where, through a country abounding with hills, consi- 
derable both in magnitude and number. 
Under this consideration, I determined to measure a portion 
of the meridian which proceeds from Dunnose to the mouth of 
the Tees ; because, from inquiry, 1 had reason to suppose it the 
