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2. An Account of an Aurora Borealis obfervedin the 
Night of the 16th 0/De cember 1737* (N.S.) at 
Padua, by [the Marquis ] Poleni, F. R. S. Commu- 
nicated in a Letter to Dr. Jurin: Tranfated 
from the Latin by T. S. M. D. F. R. S. 
HE Sky was intirely clear, not only in the 
Beginning, but during the whole Night. The 
Wind was at North; which was rather known by 
the Weather-cock, than fenfibly felt, the Air being 
very {till. The Quick filver in the Barometer flood at 
30 Dig. 24 Dec. ( Englifh Meafure) an extraordinary 
Height; fince in the Space of 14 Years, that I have 
applied with great Care toMeteorological Obfervations, 
I have but once obferved the Quickfilver at 30. 48. 
which I have hitherto looked upon as the greateft 
Height. 
In my Thermometer of Monfieur Amontoris 
Make, the Height of the Quickfilver was 48 Dig. 
78 Dec. And in Monfieur de life's Thermometer, 
which he fent me from Petersburg , (in which the 
Heights are changed by the greater or lefier Denlity 
of the Mercury, and the Meafure is taken behind the 
vacant Space at Top) I reckoned 142. 
But before l treat of the Obfervation, it becomes 
neceflary to remark Two Things, viz. that I fuppofe, 
that the Divifions of the Horizon into Degrees Eaft- 
ward and Weft ward begin from that Point, where 
the Meridian interfetts the Horizon in the North: 
And befides, when I mention the Degrees of the 
Horizon, or Degrees only, I mean thofe Diftances 
which 
