Observations upon Auroral and Optical Phenomena. 229 



Halos in January, 1835. 



Many years ago, on one excessively cold morning, there were 

 seen, upon the plain of West Point, by persons looking towards the 

 sun. upright columns of great splendor, and of prismatic hues, far 

 exceeding in brilliancy any rainbow which had ever been witnessed 

 by the individual who described this to me. Of this phenomenon I 

 cannot give a more particular description; but it was, I presume, iden- 

 tical with the one which I am about to describe. 



The morning of Jan. 5th, 1835, was excessively cold, — ■the ther- 

 mometer having been before sunrise down to 16° below zero at West 

 Point, where I then was. At a quarter before nine, A. M. I observ- 

 ed the air to be full of bright spicules, settling down upon objects like 

 the hoar frost. Being instantly reminded of the foregoing spectacle, 

 which had been formerly described to me, I went out of doors in 

 search of something similar. The air was very calm and still — 

 moving 1 should think a little from the north or northwest. Look- 

 ing towards the sun, I saw at once on each side of him, for perhaps 

 30°, the arc of a halo, of which he was the center. The arcs 

 might easily have been taken for upright columns. They were pris- 

 matic ; the violet being exterior, and the red being interior or tow- 

 ards the sun. They were nearly vertical J the brightest parts being 

 opposite the sun on each side, horizontally. I measured roughly the 

 diameter of the halo, and found (taking the average of the colors) 

 that it was just 45°. There was, in addition, a bright column, of the 

 breadth of the sun, and not prismatic, which passed perpendicularly 

 down from that luminary to the horizon, — or rather to the surface af 

 the river, which was two hundred feet below me, and one quarter of 

 a mile distant. This column was of the hue of sunlight, or twilight, 

 but rather faint, as were also all the phenomena. There was at the 

 time a smokiness in the air, like that of " Indian summer," which I 

 took at first to be the effect of the floating spiculse ; but it continued 

 visible just as plainly after they were gone. Indeed it continued 

 all the day. At twenty five minutes past nine, I re-measured the 

 halo with much care, although by rough means, and found its diame- 

 ter as before, just 45°. This result was certainly very near the 

 truth. Some time after this, its halo disappeared, although the spic- 

 ules remained in the air. The column of light which passed up to 

 the sun was not visible far, if at all, above it; but the luminous arches 

 extended, I should say from recollection, as much above their bright- 

 est point as beneath. 



