25s; the geodetic longitudes, computed from
elements which I published long ago in the Encyclopaedia
Metropolitana, are 12m 0.34s, 24m 31.47s, 41m 23.06s. It appears from
this that the elements to which I have alluded represent the form of
the Earth here as nearly as is possible. On the whole, I think it
probable that this is the best arc of parallel that has ever been
measured.
"With regard to the Maine Boundary: on May 7th Col. Estcourt, the
British Commissioner, wrote to me describing the perfect success of
following out my plan: the line of 64 miles was cut by directions laid
out at the two ends, and the cuttings met within 341 feet. The country
through which this line was to pass is described as surpassing in its
difficulties the conception of any European. It consists of
impervious forests, steep ravines, and dismal swamps. A survey for the
line was impossible, and a tentative process would have broken the
spirit of the best men. I therefore arranged a plan of operations
founded on a determination of the absolute latitudes and the
difference of longitudes of the two extremities. The difference of
longitudes was determined by the transfer of chronometers by the very
circuitous route from one extremity to the other; and it was necessary
to divide the whole arc into four parts, and to add a small part by
measure and bearing.
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