I saw through the telescope first a tiny solar crescent of intense brightness, then the halo proper, now exceedingly narrow, and then what looked like a silver terrestrial crescent, but a mere thread, finer and shorter than any that the Moon ever displays even to telescopic observers on Earth; since, when such a minute portion of her illuminated surface is turned towards the Earth, it is utterly extinguished to our eyes by the immediate vicinity of the Sun, as was soon the case with the terrestrial crescent in question.

I watched long and with intense interest the gradual change, but I was called away from it by a consideration of no little practical moment.

I must now be moving at a rate of nearly, if not quite, 40,000 miles an hour, or about a million miles per diem.

It was not my intention, for reasons I shall presently explain, ever greatly to exceed this rate; and if I meant to limit myself to a fixed rate of speed, it was time to diminish the force of the apergic current, as otherwise before its reduction could take effect I should have attained an impulse greater than I desired, and which could not be conveniently or easily diminished when once reached.

Quitting, therefore, though reluctantly, my observation of the phenomena below me, I turned to the apergion, and was occupied for some two or three hours in gradually reducing the force as measured by the cratometer attached to the downward conductor, and measuring with extreme care the very minute effect produced upon the barycrite and the discometer.