74 



EECEEATIVE SCIENCE. 



wliich. tliey would improve as experience 

 miglit direct them ; and many who have not 

 yet essayed to make friendship with Neptune 

 and the many sea and river gods that might 

 he invoked to favour the enterprise, would 

 speedily begin if certain doubts and difficul- 

 ties were removed from their minds. 



Granting tanks are properly constructed, 

 so that none of the metal used can come into 

 contact with the water, how will you place 

 them as regards the light ? I have a variety 

 of tanks ; some used for ornament, and others 

 for purposes of study only. Some of the 

 latter are objects that no casual observer 

 would tolerate ; but toleration is not expected, 

 for only a few scientific friends ever see them 

 beside myself. The most important result of 

 my experience in tank management is this 

 lesson, applicable to all kinds of vessels — 

 leave them alone. An aquarium can neither 

 look well, nor do well, whether used for orna- 

 ment or facility for scientific observation, 

 unless it is allowed very much indeed to take 

 care of itself. The whole secret of securing 

 success, is to make the first arrangements on 

 sound principles, and then to consider whe- 

 ther the light in which they are to be placed 

 is likely to prosper or ruin them. For ma- 

 rine objects there is no form of tank so gene- 

 rally safe as the " slope-back," invented by 

 Mr. Warrington. The light finds its way 

 into the water almost vertically in such a 

 vessel, and that is in accordance with Nature. 

 A cool position, safe from frost, vertical light, 

 little or no side-light, and a general if not 

 total exclusion of sunshine ; these are the 

 conditions as to light under which success 

 has been and wiU be most general. But ves- 

 sels kept for ornamental purposes cannot 

 always be so placed, and ingenuity must de- 

 vise the means of compensation. A river 

 tank will bear more light than a marine ves- 

 sel. Sunshine may be permitted occasionally 

 to stream through it, to the delight of bleak 

 and minnows, which gambol rarely when 

 the scene is thus made magical for awhile ; 



but a constant flood of fuU daylight into 

 and through a river tank quickly fouls the 

 water by inducing a rapid growth of minute 

 vegetable forms, and therefore the conditions 

 just recited should not be forgotten. Suppose 

 a rectangular tank, transparent on all four 

 sides, to be placed in a window high enough 

 for the light to pass through it. In a south 

 aspect such a vessel will become opaque in 

 ten days, and, if left alone, will become bright 

 again in a fortnight or three weeks. It will 

 then assume a muddy hue once more, and 

 thus cause vexation upon vexation, and be at 

 last pronounced a failure. But, instead of 

 thus exposing it to an excess of light, paste 

 over the side next the window a sheet of 

 green tissue-paper ; let the window be open 

 all the summer, night and day, and keep the 

 blind always down, and from the moment you 

 have adopted such an arrangement you will 

 cease to complain of the uncertainty that 

 attends the management of aquaria. Such 

 a tank, so managed, adorns the hall of my 

 residence. It is emptied, cleaned, and refitted 

 once a-year ; beyond that it has no attention 

 whatever, except an occasional cleansing of 

 the front plate of glass, and it is always 

 beautiful. The fishes in it are mostly old 

 friends, and tiiere has been but one death 

 amongst them for three years past. Some 

 years ago I had a collection of tame minnows 

 and Prussian carp. They were a thousand 

 times more worthy the admiration of a " dis- 

 cerning public" than the horrible " tallfing 

 and performing fish," which, by the way, is 

 a quadruped, and not a fish at all. Those 

 carp and minnows were transferred from a 

 cool window in a north room, where they had 

 been under instruction for the space of 

 eighteen months, to a bench in the garden, 

 over which I intended to fix a canopy of 

 calico. Alas ! the sun found his way to the 

 bench before the canopy was ready for its 

 place — the water in one day became a dark 

 mass of green confervoid soup. In three 

 days the carp were all dead, many of the 



