Parhelia. 61 



of us, it was rapidly extended to the south more than a mile, giv- 

 ing a heavy fall of rain to its extreme limit. 



I have no particular theory to support or promulgate in giving 

 you the foregoing. One of two things is perfectly clear from 

 the facts as observed by me. The first is, that there was no 

 visible rotary movement in the cloud at any time ; and the sec- 

 ond is, that there was no rush of surface air to the cloud, which 

 would seem necessary had the noise been occasioned by an in- 

 ternal or central whirl. I have never known a thunder shower 

 in which such a perfect stillness of the whole atmosphere was ob- 

 servable as during the continuance of this. Still some such move- 

 ment as this seems necessary to account, not only for the noise 

 that attended the cloud, but also for the rapid elongation of the 

 cirri, and the formation of the hail and snow. It would seem 

 that by some ascending movement, the vapor of the cloud and 

 the drops of rain were brought in contact with air below the freez- 

 ing point ; and the large drops of water that fell on the western 

 line of the shower must have been the result of a rapid conden- 

 sation of vapor by contact with air slightly above that point. Is 

 it not possible that owing to the different directions of the upper 

 and lower strata of air, a rotary or upward movement may have 

 been produced, drawing into it and elevating the vapor of the 

 upper masses of cloud, the space thus created being filled by 

 more elevated and colder masses, the motion of which to this 

 point would account for the roar, as well as show how the con- 

 densation or congelation that took place might have been produ- 

 ced ? In this case the lower air might have remained, as it cer- 

 tainly did, perfectly quiescent, while the upper air was in the 

 greatest agitation. 



Parhelia. 



January 1st was the coldest day we have thus far had this year 

 at this place. The thermometer at 7 o'clock was at — 12°, at 

 9 o'clock — 10°, and at 2 o'clock — 4°. It had snowed constant- 

 ly for about three days, and the average depth was not less than 

 three feet, the wind from the north. On the 2d, the wind was 

 N. W., the thermometer at 9 o'clock at zero, and at 2 o'clock 9° 

 above. At sundown it sunk to 0. A dense haze seemed to hang 

 like a curtain in the west, and a little before sundown, brilliant 

 parhelia were seen, resembling two mock suns. Their appear- 



