During the total eclipse the lunar disc displayed, as almost always happens, a reddish tint, without disappearing; the edges, examined with a sextant, were strongly undulating, notwithstanding the considerable altitude of the orb. It appeared to me that the moon was more luminous than I had ever seen it in the temperate zone. The vividness of the light, it may be conceived, does not depend solely on the state of the atmosphere, which reflects, more or less feebly, the solar rays, by inflecting them in the cone of the shade. The light is also modified by the variable transparency of that part of the atmosphere across which we perceived the moon eclipsed. Within the tropics great serenity of the sky and a perfect dissolution of the vapours diminish the extinction of the light sent back to us by the lunar disc. I was singularly struck during the eclipse by the want of uniformity in the distribution of the refracted light by the terrestrial atmosphere. In the central region of the disc there was a shadow like a round cloud, the movement of which was from east to west. The part where the immersion was to take place was consequently a few minutes prior to the immersion much more brightly illumined than the western edges. Is this phenomenon to be attributed to an inequality of our atmosphere; to a partial accumulation of vapour which, by absorbing a considerable part of the solar light, inflects less on one side the cone of the shadow of the earth? If a similar cause, in the perigee of central eclipses, sometimes renders the disc invisible, may it not happen also that only a small portion of the moon is seen; a disc, irregularly formed, and of which different parts were successively enlightened?