394 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
thermometer on the same principle. Advantage will be taken of the 
change to ower the height of the thermometer from 5 feet to 3 feet 
above the ground, as better representing the changes in temperature 
to which most garden crops are exposed. It should be clearly understood 
that this thermometer has nothing at all to do with the regular equipment 
of the meteorological station in the Chiswick Gardens. It has simply 
been added in order to see how far temperatures so taken are in agree- 
ment with those made with verified thermometers exposed in the orthodox 
fashion. 
A brief monthly summary of the observations taken in the Society's 
Gardens at Chiswick in 1899, for the ten months, for ivhich a cojiiplete 
set of readings was available, viz. March-December. 
March. — Very cold and very dry. The days were, as a rule, about 
1 degree colder, and the night temperatures about 4 degrees colder, than 
is seasonable. On the coldest night the thermometer on the grass showed 
20 degrees of frost. 
The rainfall was very light, being only about one-third the average 
quantity for the month. 
Mean temperature of the air in shade 
40=.0 
Highest 
G0°.7 on the 31st 
Lowest ... 
19°.5 
„ 21st 
Lowest temperature on the grass ... 
11°.6 
„ 25th 
At 1 ft. 
At 2 ft. 
At 4 ft. 
deep 
deep. 
deep. 
Mean temperature of the soil at 9 a.m. 
39°.l 
41°.0 
43°.5 
Highest 
4G^.3 
44°.2 
44^^.5 
Lowest 
35°.5 
39°.2 
42°.9 
Mean relative humidity of the air at 9 a.m. (complete saturation being 
represented by 100) 79 
Rain fell on 7 days to the total depth of ... ... ... ... 0-45 in. 
(E(iuivaleiit to about 2 gallons on each square yard of surface in the Gardens.) 
Heaviest fall on any day 0*17 in. on the 25th 
April. — Seasonable in temperature and very wet. The days were, as 
a rule, about 1 degree colder and the nights about 2 degrees warmer, 
than is seasonable. On the coldest night the thermometer on the grass 
showed 11 degrees of frost. The rainfall was heavy, being about 1 inch 
in excess of the average for the month. 
Mean temperature of the air in shade ... ... ... ... 47°.6 
Highest 64°.8onthe 1st 
Lowest 29°.6 „ 19th 
Lowest temperature on the grass 21°.0 19th 
Mean temperature of the soil at 9 a.m. 
Highest 
Lowest 
At 1 ft. 
deep. 
48°.2 
52°.2 
45°.5 
At 2 ft. 
deep. 
47°.5 
50°.2 
44°.9 
At 4 ft. 
deep. 
46°.6 
48°.l 
43°.9 
Mean relative humidity of the air at 9 a.m. (complete saturation being repre- 
sented by 100) 77 
Rain fell on 20 days to the total depth of 2-43 in. 
(Equivalent to about 11 gallons on each square yard of surface in tlie Gardens.) 
Heaviest fall on any day 0-30 in. on the 9th. 
