1821.2 Dr. Barney^ s MeteorologicalJoumalkeptat Gosport, 369 



by confining the mean barometrical pressure to particular phases 

 of the moon, which we have not now time to investigate. The 

 aggregate of the spaces described by the curve was greatest in 

 January, and least in July. The averages of all the observations 

 at eight, two, and eight o'clock every day, precisely agree with 

 each other, and are 1- 100th of an inch less than those of the 

 preceding year. 



Temperature. — The mean temperature of this year is nearly 2° 

 less than in 1819, 2^° less than in 1818, and 0'41 of a degree less 

 than in 1817 ; but about 1-1-° higher than it was in the ungenial 

 year 1816. The maximum of the two preceding years has fallen 

 off, and the minimum this year is considerably lower than at any 

 time since February, 1816. The mean heights of the thermo- 

 meter at eight, a. m. and eight, p.m. correspond within one- 

 fourth of a degree, and also with the annual mean temperature 

 within 1-1-° as usual ; but the mean at two, p. m. is nearly 4° less 

 than that at the same hour in the warm year 1818. Although 

 the sun arrives at his greatest north declination at the summer 

 solstice, when his meridional rays in this latitude are inclined to 

 the earth at an angle of about 62° 40', and have a powerful effect 

 upon a thermometer exposed to them under a clear sky; yet a 

 month is generally taken up in the exhalement of the earth's 

 moisture to a certain depth, before we experience experimentally 

 the greatest monthly mean temperature ; because the earth and 

 air do not receive their maximum heat till the latter part of July. 

 At the winter solstice, the sun has his greatest south declination, 

 when his rays are inchned to us at an angle of about 15° 44% 

 and have then the least power upon the thermometer; yet v/e do 

 not experience the lowest monthly mean temperature till Janu- 

 ary ; because the earth has not wholly parted with the heat it- 

 obtained in the summer till the middle of this month. An excep- 

 tion to these general rules, however, does sometimes occur at the 

 retrogression of the seasons, arising from untimely weather. 



De Luc's Whalebone Hygrometer. — The mean humidity of the 

 air near the ground, as ascertained by three observations each 

 day at eight, two, and eight o'clock, appears to be 1° (within 

 '1-100) drier than the warm year 1818 ! This appears incongruous 

 at first sight ; but as the amount of rain and of evaporation is 

 much less this year, the ascent of vapours must have been 

 slower and in less quantities, and consequently the lower s^ra^wm 

 of air drier upon the hygrometric substance of the instrument. 

 The mean at eight, a. m. for the last three years, is 71*16° ; and 

 the mean at eight, p. m. 72*83°. 



Prevailing Winds. — In the table containing a scale of the 

 winds, or the number of days on which they have prevailed, we 

 see that they have blown more uniformly round the points of the 

 compass this year than in the years 1818 and 1819. The winds 

 to the west of the meridian have, however, prevailed longer than 

 those on the eastern side, by about one-sixth of the whole year y 



Neta Series, vol. i. 2 a 



