30 
STUDIES OF BRITISH FRESHWATER ALG^. 
aquatics (see below) must contribute considerably to the organic 
content of the water in the latter part of the year. The water of 
the pond is ordinarily quite clear, although somewhat dark some- 
times from decaying matter. The floor is deep mud. 
Of the meteorological data the most important are those con- 
cerning temperature and rainfall. The following table gives the 
temperatures of air and water (for the first four years) at the times 
of collecting each sample, the requisite data being supplied by the 
collectors themselves. The approximate hour at which each sample 
was collected is given, wherever such information was available. 
TEMPERATURE OF AIR AND WATER AT TIME OF COLLECTION 
(in degrees centigrade). 
DATE. 
Temp. 
Air. 
Temp. 
Water. 
DATE. 
Temp. 
Air. 
Temp. 
W^ater. 
Jan. 23rd, 1904 
3° 
1° 
Sept. 
10th, 
1905 
14-5° 
17° 
(3 p.m.) 
(4 I 
).m.) 
Teb. 21st, 
5 J 
9-7° 
7-7° 
Oct. 
15th, 
53 
12-5° 
12° 
Mar. 26th, 
6° 
6-25° 
(IF 
>.m.) 
(4 p.m.) 
Nov. 
12 th, 
53 
9*5° 
9° 
Apr. 24th, 
(3.30 p.m.) 
?5 
13-5° 
12-75° 
(12.30 p.m.) 
Dec. 10th, 
53 
5-5° 
6° 
]May 29th, 
(4 p.m.) 
19° 
19-5° 
(1 : 
Jan. 
p.m.) 
7 th, 
1906 
7° 
6-5° 
June 
(3 ] 
p.m.) 
July 24th, 
^9 
9 9 
19° 
20-5° 
Feb. 
(1 1 
18ih, 
D m ^ 
33 
5° 
6° 
Sept. 7th, 
99 
16° 
17° 
Mar. 
F* 111 • ; 
18th, 
11° 
9-5° 
Oct. 2nd, 
99 
12° 
12° 
(3 I 
).m.) 
(3.30 p.m.) 
Apr. 
15th, 
5 , 
14-5° 
14° 
Oct. 30th. 
5 9 
10° 
9-5° 
(3r 
).m.) 
(3.30 p.m.) 
May 
13th, 
5 3 
23° 
19° 
Dec. 4th, 
99 
13° 
8° 
(3r 
).m.) 
(3 p.m.) 
July 
2nd, 
5 ) 
18-3° 
16° 
Jan. 1st, 1905 
2-5° 
4° 
(1 ] 
p.m.) 
(1 p.m.) 
Aug. 
10th, 
17-2° 
18° 
Feb. 5th, 
J5 
9° 
8° 
Sept. 
8 th, 
35 
28° 
23° 
(4.30 p.m.) 
Mar. 11th, 
9-5° 
8° 
Nov. 
4th, 
’3 
8° 
6-50 
(3.30 p.m.) 
n 
Jan. 
6th, 1907 
80 
40 
Apr. 16 th, 
35 
14-5° 
12° 
Mar. 
6th, 
35 
100 
80 
(12.30 p.m.) 
May 
1st. 
120 
150 
May 14th, 
35 
14-5° 
15° 
June 
28th, 
16-20 
190 
(2.30 pm.) 
June 18th, 
18° 
17*5° 
Aug. 
1 
5 
55 
— 
11-350 
(4 p.m.) 
Oct. 
4th, 
55 
11-40 
July 9th, 
35 
22-5° 
21° 
Nov. 
18th, 
55 
7.50 
70 
(3.30 p.m.) 
Aug. 13th, 
35 
16-5° 
18° 
(1 p.m.) 
A scrutiny of 
this table shows 
that the temperature of the water 
follows the changes in the temperature of the air fairly closely, and 
On tliese occasions no temperature-data were obtained. 
