meteorology. 
389 
1810-13, at Plantation House, 1500 ft. above the sea, as 3P63 in. 
of rain. 
And other records show that in the year 1862 the fall was 
at Ladder Hill, on the j qqq q._ a ^ ove the sea, 18*85 in. of rain, 
sea coast . . . 
in James’ Valley . . 250 do. 9*00 do. 
An average of thirty inches may be taken as a mean annual fall, 
but with so great a variation in different localities, it affords a figure 
of little value. The mean annual average at Longwood during five 
years was 4719 inches, the greatest occurring in 1842, and the lowest 
in 1845, the former measuring 90*46, and the latter 19*41 inches. 
It has been considered that 140 days out of the year are rainy 
days j but the high central ridge is scarcely ever four-and-twenty 
hours without clouds resting on it, and distilling moisture. 
Very little, indeed scarcely any, barometric pressure is exer- 
cised, but it is very systematic and regular. The mean pressure 
during five years at Longwood was observed to be 28'2S5 in. lhe 
greatest observed depression was 28*094 in., on the 14th March, 1843; 
and the greatest elevation 28*497 in., on the 9th July, 1842 : giving 
0*403 in. as the extreme range. March, being the lowest month, 
showed a mean of 2S*232 in. ; and July, the highest, 28*367 in. ; so 
that the range in the different months was 0*135 in. The mean 
diurnal variation being recorded at *074 in. It has been noticed 
that during those months when the barometer is highest, the tempe- 
rature is lowest, and when the barometer is lowest, the temperature 
is highest. The mean height of the barometer at the sea level, at 
Prosperous Bay, was 30*08 in.f 
During five years the mean elastic force of aqueous vapour 
at Longwood was *470 in. ; the mean in the different months varied 
from a maximum of *559 in. in March, to a minimum of *411 in. m 
August. The range in the different months was *148 in., and the 
diurnal range *032 in. \ 
The mean gaseous pressure, on dry air, obtained by deducting 
the elastic force of the vapour from the total barometric pressure was 
found to be 27*816 in., with a minimum in March ot 27*666 m 
and a maximum in July of 27 018 in. The range in the different 
months was -282 in., and the diurnal range -074 m.S 
* Appendix, p. 400. 
t Appendix, p. 401. 
§ Appendix, p. 403. 
J Appendix, p. 402. 
