Even the difference between 200 and 201 radii of elevation or apogaic distance was not easily perceptible on either.

It took, of course, much more minute observation and a much longer time to test the effect produced by the regulation of the movement, since whether I traveller forty, forty-five, or forty-two thousand miles in the course of one hour made scarcely any difference in the diameter of the Earth's disc, still less, for reasons above given, in the gravity.

By midnight, however, I was satisfied that I had not attained quite 1,000,000 miles, or 275 terrestrial radii; also that my speed was not greater than 45,000 miles (11-1\4 radii) per hour, and was not, I thought, increasing.

Of this last point, however, I could better satisfy myself at the end of my four hours' rest, to which I now betook myself.
I woke about 4h.30m., and on a scrutiny of the instruments, felt satisfied that I was not far out in my calculations.

A later hour, however, would afford a more absolute certainty.