O16 On Clouds. (Marcu, 
ArticLe VII. 
Observations on Clouds, &¥c. By Mr. Johnson, Surgeon, of 
Lancaster. 
(To Dr. Thomson.) 
SIR, 
Tue following remarks are submitted to your notice, in the hope 
that some of them may be deemed worthy of insertion in your 
Annals of Philosophy. 
T, On two Species of Cloud. 
1. In aserene sky, when there is no wind, a long and narrow 
band of white cloud may sometimes be observed stretching almost 
across the heavens, at a considerable elevation. One margin is 
thick and well defined; the other melts gradually off into a fine 
fleecy ragged edge; the thicker margin is always to windward with 
respect to the approaching rainy weather, of which this is one of 
the earliest and most certain harbingers. Each extremity appears 
to taper into an acute point. Probably this cloud floats very high 
in the atmosphere, and extends itself very far; in one instance it 
was noticed about the same time at Preston and Lancaster, its 
centre appearing vertical at both places, which are upwards of 20 
miles distant from each other. 1 would term this a lanceolate 
cloud, although, as above described, it is, more correctly speaking, 
ligulate; but other varieties pass into an e/liptical, an oval, and 
even a friangular form ; all, however, are distinguished by a thick, 
well defined margin to windward, and a pointed extremity. ‘The 
elliptical and oval varieties are well known hereabouts by the name 
of “ Noah’s Ark,” either from their shape resembling the hori- 
zontal section of a canoe, or more figuratively because their ap- 
pearance foretelis rain and floods. ‘The triangular form is only an 
incomplete variety, generally of a darker colour, accompanied by 
other clouds, by wind, a falling barometer, and other indications 
of approaching rain. 
2, Near the horizon, between north and north-west, or about 
the magnetic pole, a very remarkable cloudy appearance sometimes 
presents itself. Its shape may be compared to a man’s hand, the 
palm just emerging above the horizon, and long tufts expanding 
like fingers ; these tufts, and of course the more dense parts of the 
cloud, are of a dark brown or black colour, Neither this, which 
may be termed the plumose, nor the lanceolate ¢loud just described, 
affects any particular time of the day or night; but I am not certain 
of having observed the former during winter, whilst the finest or 
most ligulate specimens of the latter have occurred towards the 
close of a frost. Both, however, seem worthy of notice as early 
harbingers of an impending change to bad weathers, occurring at 4 
