532 NATURE 
from a scientific point, of the one from which that at 
Brighton is copied, and even in the former case is asso- 
ciated with serious drawbacks and disadvantages, which 
forbid it from yielding in compensation for the outlay and 
labour expended the results realised by those constructed 
on later and more approved principles. It is impossible, 
for instance, to keep in health at the Brighton Aquarium 
the number of fish in comparison to the size of any given 
tank as will be found in the aquarium at the Crystal 
Palace or that of Hamburgh, or Copenhagen, or any 
other constructed on the same principle, though at the 
same time it is essential to remark, that lately the capa- 
bilities of the Brighton tanks have not been turned to 
their greatest advantage, as instanced in No. 6, holding 
110,000 gallons of water, which for many weeks past has 
‘been occupied by but three dogfish, a ray, anda few turtle 3 
No. 11, with 9,000 gallons, by two mackerel, and so on, 
A remaining still greater source of dissatisfaction asso- 
ciated with the non-circulatory system, and yet one 
capable, perhaps, of full appreciation by those only who 
have held practical aquarium responsibility, arises from 
the difficulty, verging upon the impossibility, of maintain- 
ing the tanks uniformly bright and clear throughout the 
building. Some fish foul the water to a much greater 
extent than others, notably the Flat-fish or Pleuronectide, 
who in a few weeks will render a clear isolated tank too 
opaque for the opposite side some twenty feet distant to 
be discerned. The only existing remedy for such a case 
is to run off the water and supply fresh from the reservoirs 
beneath ; but this water being drawn from the shore-line, 
the feeding pipe remaining exposed at half tide, is neces- 
sarily loaded with impurities, which re-agitated by the 
action of pumping involves the lapse of several more 
days before the tank is in a fit state for exhibition, At 
the suggestion of my predecessor, the late Mr. J. K. Lord, 
oysters and other bivalve mollusca were introduced into 
the tanks for the purpose of removing the organic par- 
ticles which rendered the water turbid, but though these 
have proved of great service, the root of the evil remains 
undisturbed, and it is only by the application of the cir- 
culatory system, securing with it the more thorough oxy- 
2 of the water, that the problem is to be effectually 
solved. 
This system, initiated by Mr. W. A. Lloyd at the 
Hamburgh Aquarium, and now maintained under his 
personal superintendence at the Crystal Palace, consists 
in having, in the first place, a bulk of water in the reser- 
voirs beneath exceeding by four or five times the total 
amount contained in the tanks above, and which, being 
pumped up by steam power and circulated through the 
building, takes up in its course by exposure to the atmo- 
sphere an amount of oxygen, permitting the preservation 
in health not only of a much larger number of inhabitants 
to each tank, but at the same time communicates to the 
water a degree of clearness and brilliancy unattainable 
by other means, and which brilliancy is increased or 
diminished in exact proportion to the uniformity and force 
of the current s) maintained. One theoretical objection 
urged by the architect of the Brighton Aquarium against 
the circulatory system, is that in the event of paint or 
other deleterious substance falling into any one tank the 
water of the neighbouring tanks would suffer equally. 
Practically, such mishaps have no business to occur, and 
though in such a case, on the “siphon” mode of circula- 
tion first attempted but abandoned as impractical at 
Brighton, some mischief might be done, it would be im- 
possible under that to be presently suggested as still 
feasible at the institution here under consideration, and 
until the adoption of which the Brighton Aquarium can- 
not be expected to fully realise the highest anticipations 
of its promoters, while the greater or less turbidity of its 
tanks must continue as hitherto a constant source of dis- 
satisfaction to the directors, and of anxiety and mortifica- 
tion to the officers held responsible, 
F 6. 1.—Front View of Tank No. 6 (110ft. long), Western Corridor, Brighton Aquarium. 
