uncommon Darknefi, on May 19, 1780. 239 
wich,—the black afhes of burnt leaves, without any cna 
ous, or other mixtures.* 
Being apprehenfive whether there was not fome uncommon 
matter in the air that day, I put out feveral fheets of clean pa- 
per in the air and rain. When they had been out four or five 
hours, I dried them by the fire. They were much fullied, and 
became dark in their colour ; and felt as if they I had been rub- 
Bed with oil or greafe. But upon burning them, there was not 
ex appearance of fulphureous or nitrous particles. 
'The motion. and fituation of the vapours in the konihi 
was alfo worthy of notice. In moft places it was very evident 
that the vapours were defcending from the higher parts of the 
atmofphere towards the furface of the earth. A gentleman, 
who was then at Pépperrell,t mentions a very curious obferva- 
tion, as to their a/Cez? and fituation. About nine o'clock 
(fays he) in the morning, after a fhower, the vapours rofe from 
the fprings in the low lands, in greztabundance. I took no- 
tice of one large column that afcended with great rapidity, to 
a confiderable height above the higheft hills, and foon fpread 
into a large cloud ; then moved off a little to the weftward. 
A fecond cloud was formed in the fame manner, from the fame 
fprings, but did not afcend fo high as the firft: and a third 
was formed from the fame places, in lefs than a quarter of an 
hour after the fecond.. About three quarters of an hour after 
nine o'clock, thefe clouds exhibited a very romantic appearance. 
The upper cloud appeared of a redih colour: the fecond ap- 
peared, 
* The fame was obferved at Concord and Dover in New- Hampfhire : at Benity : 
and many other places in this Rates 
t Mr. Eames, a Tator in the Univerfity. : 
