aquaria: their present, past, and future. 263 
Formula No. 5. 
A 1 , 
. B 4 . 
Mean result 
63° F. 
59 99 6 . 
A 1 
. B 5 . 
55 
55 
62*5° F. 
55 55 7. 
A 1 
. B 20 . 
55 
55 
60*7° F* 
Indeed if b were one hundred times as large as A, and were 
kept at 50° F., then a might be in an atmosphere at 212° F. 
(the heat of boiling water), and yet its water would he only 
52*12° F., and the most delicate English animals would live in it. 
At Nottingham is an aquariam where the show-tank and reser- 
voir spaces have had to be made as 13 is to 1. From Bunsen’s 
tables in his “ Gasometry,” page 288, may be ascertained the 
amount of atmospheric air which water in open vessels will 
absorb at given temperatures, the barometer being at 39"; 
and I here reproduce his figures, having converted his Cen- 
tigrade scale into Fahrenheit and Reaumur scale for the benefit 
of English, German, and Spanish readers. 
Bulk of water = 1* 
Temperature. 
Air 
Temperature. 
Air 
C. 
R. 
F. 
absorbed. 
C. R. 
F. 
absorbed. 
10 = 
8 
= 
50. . 
, 0-0195 
16 = 12-8 
- 60*8 . 
0*0177 
11 = 
8-8 
= 
51*8 . 
, 0-0192 
17 = 13*6 
= 62-6 . 
0-0175 
12 = 
9*6 
= 
53-6 . 
0*0188 
18 = 14-4 
= 64-4 . 
0-0173 
13 = 
10-4 
= # 
55*4 . 
00185 
19 = 15-2 
= 66-8 . 
00172 
14 = 
11*2 
= 
57*2 . 
00182 
20 = 16* 
= 68 . 
0-0170 
15 = 
12 
= 
59 . 
0-0180 
And therefore as the more air there is in the water the better 
it is, hence the value of large and therefore cool reservoirs. In- 
pedendently of all this, however, the larger the bulk of water, and 
the more constant and vigorous the circulation and aeration, the 
less it will be sullied by the animals which live in it. In the 
Crystal Palace Aquarium we have in the show-tanks 20,000 gal- 
lons of sea-water, and in the reservoir 100,000 gallons, total 
120,000 gallons, supplied by Mr. W. Hudson in 1870. Yet in 
this comparatively small quantity of unchanged fluid we have, 
from Sept. 1871 to March 31, 1876 (four and a half years), given 
to the animals in it the following enormous quantity of food with- 
out the water being otherwise than always sparklingly clear : — 
* The water in the Crystal Palace aquarium has a very small range of 
from 52° F. in very cold, to 61° F. in very hot, weather. In April last 
(1876) we had, at Sydenham, blue skies, a bright sun, and an oppressive 
warmth, with 74° F. in the shade, on the 8th of the month. On the 12th, 
four days after, we had a leaden firmament, and clouds of blinding snow 
and sleet driven by a bitter north-east wind, with the thermometer at 29° F., 
giving so great a range as 45° F. within a week. Yet the water in the 
aquarium had a range of only 1° F. = 54° F. to 53° F. 
