222 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
‘These occasional inundations effectually prevent the formation of 
the nests of the black or leaf-cutting ants, probably the greatest 
foe to wood-planting in Uruguay. 
The soil of San Jorge district is of very varied character, in 
some parts a deep, stiff, black clay, difticult to work, but very rich; 
in others light black loam, intermixed with sand; there are also 
some patches of gravelly soil, apparently old moraines, excellent 
for trees ; and in some parts a cold grey clay occurs, pretty deep, 
that holds water long, never grows good grass, and is our worst 
land. The stone is chiefly amygdaloidal; there is also a good 
deal of conglomerate sandstone ; some true felspathic sandstone, 
approaching tuffa in composition ; a little quartzite, grey and liver 
coloured ; and there is also a dyke running across, of close-grained 
voleanic rock, 
Meteorological.—The mean annual temperature, as ascertained 
by me from nine years’ observations, taken at San Jorge by the 
generally received scientific methods, is 60°°9 F.; spring and 
autumn averages running from 72° maxima to 49° minima, 
summer from 84°°7 to 58°-4, and winter from 60°5 to 41°:3. 
December, January, and February are taken as summer months, 
June, July, and August as winter months. The highest shade 
temperature recorded in nine years is 101°, and the lowest 23°. 
The daily range of temperature for spring and autumn is 22°3, 
for summer 26°°3, and for winter 19°°2, The average annual 
rainfall is 46 inches, falling on 94 days, and with a duration of 
329 hours per annum, April is the rainiest month, and then 
September ; February being the driest. There is an amount of 
cloud of 1670 out of a possible 3650; thus it may be said that 
on 4 days out of 9 clouds hide a sky, which for the other 5 days 
is cloudless. There is an annual average of 2836 hours of sun- 
shine out of a possible 4368} hours. The average dew-point 
ranges between 48°°3 for winter to 60°-9 for summer, and relative 
humidity from 53°°6 for summer to 78°:2 for winter; spring and 
autumn averages being at almost equal points between summer 
and winter. It is not at all infrequent to find an inch of rain 
falling in one hour; 3 or 4 inches have also been measured for 
durations of five and six hours, The two years July 1886 to June 
1888 gave 65 inches of rain, or 32} inches per annum, whereas 
the twelve months July 1888 to June 1889 gave 79 inches. 
These meteorological notes, extracted from a record of nine years, 
show that the climate is variable, and its extremes accentuated. 
