Meteorological Essays and Observations. 341 
which there is every reason to suppose have been occasioned by 
atmospherical changes, and consequently, as we have observed in a 
former part of this article, if these variations, barometrical, thermo- 
metrical, and hygrometrical, were carefully and regularly arranged 
at corresponding periods, and the changes in the condition of public 
health accurately marked, some very interesting and valuable informa- 
tion might in ali probability be obtained, not less important to the 
physician than to mankind in general, 
We can only enumerate here these general characters of the climate 
as adduced by Mr. Daniell, on an average-of three successive years. 
The monthly phenomena are given, accompanied with popular obser- 
vations on the corresponding conditions of the weather, the state of 
vegetation, health, &c.: but for those we must refer the reader who 
may be anxious to peruse them, to the work itself. 
‘The observations were made three times a day, viz., from eight to 
ten o’clock A. M., from half past three to half past five P. M., and 
from ten to half past eleven P. M. 
The mean pressure of the total atmosphere as denoted by the baro« 
meter was found to be 29,881 inches: the mean of twenty years, 
deduced by Mr. Howard from the observations of the Royal Society 
being 29.8655 inches. The mean temperature derived from the 
daily maxima and minima of the thermometer was 4,9°.5, correspond= 
ing even to the decimal place with Mr. Howard’s estimate. The 
mean dew-point was 44°.5, as also calculated from the daily maxima 
and minima. The elastic force of the vapour was consequently 
0.334 inch, and a cubic foot of the air contained 3.789 grains of 
moisture. ‘The degree of moisture was represented by 5° upon the 
thermometric scale, and the degree of moisture by 850 upon the 
hygrometric. The average quantity of rain was 22.199 inches, and 
the amount of evaporation calculated from the hygrometer, 23.974 
inches; and the weight of water, raised from a circular surface of 
six inches diameter, 0.31 grains per minute. 
The Barometric range was from 30.82 inches to 28.12 inches : the 
range of the dew-point from 70° to 11°. The pressure of the vapour 
varying with it from 0.770 inch, to 0.103 inch. The maximum tem- 
perature of the air was 90°, the minimum 11°, The force of radiation 
from the sun averaged 23°.3 in the day, and that from the earth at 
night 4°.6: the highest temperature of the sun’s rays was 154°, and 
the lowest temperature on the surface of the earth 5°. The greatest 
degree of dryness was 29°, or the least degree of moisture upon the 
hygrometric scale 389. The time of the day was found, in some 
degree, to influence the near results; and one of the most constant 
eflects was that produced upon the barometer. The mercurial column 
reached its greatest height in the morning, declined to its lowest in 
the afternoon, and again rose at night. The average difference of 
these periods, as exhibited by the journal, was as follows :—Morning 
above night +.005 inch ; afternoon below morning —.015 inch ; 
