impulse derived from the Earth; so that thenceforward I should be entirely free from the influence of the latter, though still sharing that motion of the Earth through space at the rate of nearly nineteen miles per second, which would carry me towards the line joining at the moment of opposition her centre with that of Mars. All went as I had calculated. I contrived to arrest the Astronaut's motion at the required elevation just about the moment of sunset on the region of the Earth immediately underneath. At 12 P.M., or 24h by the chronometer, I directed a current of the requisite strength into the eastward conductor, which I had previously pointed to the Earth's surface, but a little short of the extreme terrestrial horizon, as I calculated it. At 1 A.M. I found myself, judging by the stars, exactly where I wished to be, and nearly stationary as regarded the Earth. I instantly arrested the eastward current, detaching that conductor from the apergion; and, directing the whole force of the current into the downward conductor, I had the pleasure of seeing that, after a very little adjustment of the helm, the stars remained stationary in the mirror of the metacompass, showing that I had escaped from the influence of the Earth's rotation. It was of course impossible to measure the distance traversed during the invisibility of the Earth, but I reckoned that I had made above 500 miles between 1h. and 2h. A.M., and that at 4h. I was not less than 4800 miles from the surface. With this inference the indication of my barycrite substantially agreed. The latter instrument consisted of a spring whose deflection by a given weight upon the equator had been very carefully tested. Gravity diminishing as the square of the distance from the centre, it was obvious that at about 8000 miles—or 4000 above the Earth's surface—this spring would be deflected only one quarter as much by a given weight as on Earth: at 16,000 miles from the surface, or 20,000 from the centre, one-twenty-fifth as much, and so on. I had graduated the scale accordingly, and it indicated at present a distance somewhat less than 9000 miles from the centre. Having adjusted the helm and set the alarum to wake me in six hours, I lay down upon my bed. The anxiety and peril of my position had disturbed me very little whilst I was actively engaged either in steering and manipulating my machinery, or in looking upon the marvellous and novel spectacles presented to my eyes; but it now oppressed me in my sleep, and caused me frequently to wake from dreams of a hideous character. Two or three times, on such awaking, I went to examine the metacompass, and on one occasion found it necessary slightly to readjust the helm; the stars by which I steered having moved some second or two to the right of their proper position.