"The length of the pendulum and that of the meridian are the two principal means offered by Nature for fixing the unity of linear measurements. Both being independent of moral revolutions, they can undergo no detectable alteration short of enormous changes in the physical constitution of the earth. The first method is easily applicable, but has the disadvantage of making the measurement of distance depend on two elements that are heterogeneous to it, gravity and time, the division of [the latter of] which, moreover, is arbitrary. It was decided, therefore, to adopt the second method, which appears to have been employed in early antiquity, so natural is it for man to relate the units of distance by which travels to the dimensions of the globe that he inhabits. In moving about this globe, he may thus know by the simple denomination of the distance the proportion it bears to the entire circumference of the earth. This has the further advantage of making nautical and celestial measurements correspond. The navigator often needs to determine, one from the other, the distance he has traversed and [the length of] the celestial arc lying between the zenith at this point of departure and that at his destination.It is important, therefore, that one of these magnitudes should be the expression of the other, with no difference except in the units. But to that end, the fundamental linear unit must be an aliquot part of the terrestrial meridian, which corresponds to one of the divisions of the curcumferance.Thus the choice of the meter came down to that of unity of angles."