The Meteorology of Whitehaven. 379 
13th and 22d of December, with the wind at ESE. At Carlisle, the 
minimum (9°) occurred on the night between the 5th and 6th of Feb- 
ruary, when the minimum at Whitehaven was 33°, a difference of tem- 
perature of 24° between two places, about 40 miles distant from each 
other. We have on former occasions alluded to the decided superiority 
which this town possesses over many others in the southern and south- 
eastern counties of England, in the greater warmth and less variable 
character of its climate, especially during the winter season. But it 
maintains this advantage over most, if not every other town in the same 
county, even those situated within a few miles of the sea. During the 
late frost, the thermometer at Wigton, 30 miles NE. of Whitehaven, 
was frequently 14°, 15°, and even 17° lower in the nights. 
Drw-Porn7, &c.—The mean complement of the dew point, or the 
difference between the temperature of the air and that of the vapour 
which it holds in mechanical combination (5°.66), indicates a drier state 
of the atmosphere than in the previous year; but 1842 stands higher 
than either in point of hygroscopic dryness. Now the fall of rain is ex- 
actly in accordance with the indications of the hygrometer: last year 
9.843 inches less rain fell than in 1843, and 1842 received 2.030 inches less 
than in 1844, and 11.513 inches less than in 1843. Andas the rate of the 
production of vapour proceeds, ceteris paribus, in the inverse ratio to the 
quantity of moisture already suspended in the atmosphere, we find ac- 
cordingly, that the mean evaporating force is, in 1842, 25,8 grains; in 
1844, 20.8 grains; and in 1848, 20.36 grains per hour. 
Evaporation GAucu.—It may appear somewhat anomalous, that 
whilst the quantity of water throwu off in the form of elastic vapour is 
31.719 inches, an increase of 5.262 inches on the previous year, the mean 
evaporating force continues nearly the same. This discrepancy between 
estimation and absolute measurement, is chiefly occasioned by the in- 
creased action of the sun’s rays in 1844 over 1843, which, it is obvious, 
cannot be taken in as an element in computing the evaporating force. 
Last year the fall of rain exceeds the evaporation only by five inches: 
in 1843, the excess of rain was nearly twenty inches. The greatest 
amount of evaporation occurs in May, and the least in December. It may 
be worthy of remark, that the evaporation in December 1844 (.800), 
with a mean temperature at the freezing point, is exactly the same as in 
the corresponding month of 1843, with a mean temperature 10° higher, 
but in conjunction with an excessively damp, foggy atmosphere. The 
evaporation exceeds the fall of rain in no less than four months of last 
year, viz., May, July, August, and December; and in three other 
months, viz., April, June, and Nuyember, the deposition and absorption 
are nearly equal. In this wet locality such a circumstance probably 
does not occur more than once in a quarter of a century. 
RaDIATION.—The amount or effect of terrestrial radiation is deter- 
mined by exposing a self-registering thermometer on the grass, under a 
clear or cloudless sky, and comparing its indications with those of a 
similar instrument, covered at the top, about four feet from the ground. 
The difference exhibits the depression of temperature produced in the 
superincumbent stratum of air, by the free radiation of heat from the 
earth’s surface, From a series of observations carried on almost every 
night when the weather permitted, we give below the maximum or 
greatest amount of radiation in each month, premising that in the first 
four months of the year, the thermometer was exposed on the soil, and 
during the other eight months on the grass :— 
Maximum of Terrestrial Radiation.— January 23d, 6°.5 ; Feb. 12th, 
7°; March 21st and 28th, 8°; April 7th and 12th, 8°.5 ; May 26th, 12°; 
June 4th, 9°; July 15th and 23d, 11°.5; August 27th, 11° ; September 
20th, 9°.5; October 28th, 11°; November 21st, 10°.5; December 3d, 11°. 
