one from another, that there is no certainty in trusting any of
them. The most common and received opinion is that the circuit of
the earth is 21600 miles, reckoning 60 miles for every degree,
and then the depth or Diameter of the Earth shall be 6877 English
miles, containing 5000 foote in a mile.

The means wherby the circuit and Diameter of the earth are found
out are principally two.

1 By measuring North or South, vnder one Meridian some good
quantity of ground, threescore or an hundred miles (or two for
the more certainty) for in those petty observations of small
distances there can be no certaine working. This may be done,
though it be laborious, yet exactly without any sensible error by
a skilfull workeman, plotting it out vpon his paper, with due
heed taken, that hee often rectifie the variation of the needle
(by which he travells) vpon due observation, and that all notable
ascents and descents, with such winding and turning as the
necessity of the way causeth, be reduced to one streight line. By
this means wee shall know how many miles in the Earth answering
to a degree in the Heauens; if exact observation by large
instruments be made to finde the elevation of the pole, in the
first place where wee begin to measure, and the last where wee
make an end.

Besides this way of measuring the circumference of the Earth,
there is none other that hath any certainty of observati[~o] in
it. That by Eclipses is most vncertain, for a little error in a
few minuts of time (which the observers shall not possibly
avoide) breeds a sensible and fowle error in the distance of the