The Latter Is Invariably Attended With A Coloration Of Light.

It is remarkable enough, that, in northern countries, at a time when the atmosphere appears perfectly dry, the scintillation is most decided in very cold weather.) It was curious that the vapour did not affect the hygrometer at the surface of the earth.

I remained a part of the night seated in a balcony, from which I had a view of a great part of the horizon. In every climate I feel a peculiar interest in fixing my eyes, when the sky is serene, on some great constellation, and seeing groups of vesicular vapours appear and augment, as around a central nucleus, then, disappearing, form themselves anew.

After the 28th of October, the reddish mist became thicker than it had previously been. The heat of the nights seemed stifling, though the thermometer rose only to 26 degrees. The breeze, which generally refreshed the air from eight or nine o'clock in the evening, was no longer felt. The atmosphere was burning hot, and the parched and dusty ground was cracked on every side. On the 4th of November, about two in the afternoon, large clouds of peculiar blackness enveloped the high mountains of the Brigantine and the Tataraqual. They extended by degrees as far as the zenith. About four in the afternoon thunder was heard over our heads, at an immense height, not regularly rolling, but with a hollow and often interrupted sound. At the moment of the strongest electric explosion, at 4 hours 12 minutes, there were two shocks of earthquake, which followed each other at the interval of fifteen seconds. The people ran into the streets, uttering loud cries. M. Bonpland, who was leaning over a table examining plants, was almost thrown on the floor. I felt the shock very strongly, though I was lying in a hammock. Its direction was from north to south, which is rare at Cumana. Slaves, who were drawing water from a well more than eighteen or twenty feet deep, near the river Manzanares, heard a noise like the explosion of a strong charge of gunpowder. The noise seemed to come from the bottom of the well; a very curious phenomenon, though very common in most of the countries of America which are exposed to earthquakes.

A few minutes before the first shock there was a very violent blast of wind, followed by electrical rain falling in great drops. I immediately tried the atmospherical electricity by the electrometer of Volta. The small balls separated four lines; the electricity often changed from positive to negative, as is the case during storms, and, in the north of Europe, even sometimes in a fall of snow. The sky remained cloudy, and the blast of wind was followed by a dead calm, which lasted all night. The sunset presented a picture of extraordinary magnificence. The thick veil of clouds was rent asunder, as in shreds, quite near the horizon; the sun appeared at 12 degrees of altitude on a sky of indigo-blue. Its disk was enormously enlarged, distorted, and undulated toward the edges. The clouds were gilded; and fascicles of divergent rays, reflecting the most brilliant rainbow hues, extended over the heavens. A great crowd of people assembled in the public square. This celestial phenomenon, - the earthquake, - the thunder which accompanied it, - the red vapour seen during so many days, all were regarded as the effect of the eclipse.

About nine in the evening there was another shock, much slighter than the former, but attended with a subterraneous noise. The barometer was a little lower than usual; but the progress of the horary variations or small atmospheric tides, was no way interrupted. The mercury was precisely at the minimum of height at the moment of the earthquake; it continued rising till eleven in the evening, and sank again till half after four in the morning, conformably to the law which regulates barometrical variations. In the night between the 3rd and 4th of November the reddish vapour was so thick that I could not distinguish the situation of the moon, except by a beautiful halo of 20 degrees diameter.

Scarcely twenty-two months had elapsed since the town of Cumana had been almost totally destroyed by an earthquake. The people regard vapours which obscure the horizon, and the subsidence of wind during the night, as infallible pregnostics of disaster. We had frequent visits from persons who wished to know whether our instruments indicated new shocks for the next day; and alarm was great and general when, on the 5th of November, exactly at the same hour as on the preceding day, there was a violent gust of wind, attended by thunder, and a few drops of rain. No shock was felt. The wind and storm returned during five or six days at the same hour, almost at the same minute. The inhabitants of Cumana, and of many other places between the tropics, have long since observed that atmospherical changes, which are, to appearance, the most accidental, succeed each other for whole weeks with astonishing regularity. The same phenomenon occurs in summer, in the temperate zone; nor has it escaped the perception of astronomers, who often observe, in a serene sky, during three or four days successively, clouds which have collected at the same part of the firmament, take the same direction, and dissolve at the same height; sometimes before, sometimes after the passage of a star over the meridian, consequently within a few minutes of the same point of true time.* (* M. Arago and I paid a great deal of attention to this phenomenon during a long series of observations made in the year 1809 and 1810, at the Observatory of Paris, with the view of verifying the declination of the stars.)

The earthquake of the 4th of November, the first I had felt, made the greater impression on me, as it was accompanied with remarkable meteorological variations. It was, moreover, a positive movement upward and downward, and not a shock by undulation.

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