122 



HARDWICKE'S SCIENCE-GOSSIP. 



[June 1, 1870. 



box was stood up by the side of the aquarium, 

 reaching considerably higher than it. Secondly, a 

 gallon of sea-water was made to run off daily by 

 means of a siphon into a gallon bottle, which, when 

 full, was lifted up into the box, and was emptied 

 into the aquarium again, gradually, by means of a 

 siphon armed with a small glass jet, from which the 

 water ran in a small stream for some time. 



The advantages of this aquarium were : — 



Firstly and principally, the water was better 

 aerated, and with less trouble. 



Secondly, there was a dark chamber which kept 

 a great portion of the water cool and fresh. 



Thirdly, objects could be conveniently magnified 

 through the glass. 



Fourthly, the view from the front of the aquarium 

 was very good. 



This aquarium contained a dozen specimens of 

 Actinia Mesembryanthemum, two ascidians, two 

 hermit crabs, two shrimps, one blenny. 



Not long afterwards I obtained a good many 

 hermit crabs, and bought a separate glass globe for 

 them. They afforded me much amusement, and 

 would contest desperately for a piece of meat. On 

 throwing a fragment near one of them, it would at 

 first appear unconscious of the presence of such a 

 luscious morsel, which it would, however, not be 

 long in discovering, when it would dash frantically 

 at it, and having secured it with the large claw, 

 would then pick tiny pieces out of it with the 

 smaller one. It is a curious thing that a hermit 

 crab having left its shell seems to recognize it again 

 by some means, for I used often to drive one of 

 them out of its shell to show the ludicrous manner 

 of getting into it 'again : this was done by gently 

 tapping upon it, when, after a series of taps, it ulti- 

 mately left it in a jerky fashion. Its manner of 

 creeping in again is as follows : — On approaching it, 

 it feels it all over with its claws, and being satisfied 

 with its identity, throws it over and gets into it 

 backwards, then with a flourish of its legs the shell 

 rolls over, and the crab is again on its legs. 



My present aquarium, which will form the prin- 

 cipal subject in this paper, was established in the 

 spring of 1SG9. It is a propagating-glass of twenty 

 inches in diameter, and about thirty inches in 

 height, capable of holding from eighteen to twenty 

 gallons. The portion which has the knob rests upon 

 a basket filled with fine mould, above which is a 

 strip of blanket to take off the strain. For the 

 sake of better aeration, only six gallons of sea-water 

 are kept in it. Fitting the bottom of the aquarium 

 and lying parallel with it is a piece of circular slate. 

 This piece of slate has near its centre two holes 

 bored into it, and into these two little wooden plugs 

 are driven, which project upwards. Resting upon 

 these plugs, and inclined towards the back of the 

 aquarium, is another piece of slate, to which an 

 oyster-shell has been cemented with hot gutta- 



percha, forming a capital ledge for the suspension 

 of seaweeds, zoophytes, etc. The light is stopped 

 off in this aquarium in the same manner as in the 

 former one, and the latter piece of slate forms a 

 good dark chamber. 



It so happened that in the room which I had 

 chosen for this aquarium there was a cupboard near 

 the window, and high up in the wall. I took advan- 

 tage of this fact and nailed some thin gutta-percha 

 tubing from this cupboard along the wall to the 

 aquarium, over which it hung at a distance of a few 

 inches, and was provided with a small glass jet, 

 which came to a fine point, and which had a small 

 orifice. This is the arrangement for the aeration of 

 the water ; for drawing it off there is a separate 

 gutta-percha tube, extending so far into the water 

 as just to draw off a gallon of water, and when I 

 wish to aerate that remaining in the aquarium, I 

 place a gallon bottle at this latter tube, and no 

 sooner is it full, than I lift it up to the cupboard, 

 which is fully three feet higher than the aquarium, 

 and place that portion of the tube which is therein 

 into the bottle, and gently suck that end over- 

 hanging the aquarium, when the water soon com- 

 mences running from the jet in a fine stream, and 

 with great force driving a shower of minute air- 

 bubbles to the depths. 



The water is tested daily by means of a small 

 specific-gravity test, and according to the amount 

 of its evaporation so much fresh water is added. 



This marine aquarium contains — a little shore 

 crab {Carcinas Manas) ; a good many marine Cy- 

 clops ; a young rock limpet {Patella vulgaris) ; 

 some young mussels ; a dog-winkle {Purpura) ; 

 a fine colony of Halodactylus, upon a piece of wrack 

 {F/tcus serratus) ; Bowerbanlcia imbricata ; Pedicil- 

 Hntt Belgica (large specimens) ; Scrpula contort upli- 

 cata ; Spirorbis communis; colonies of Spio seti- 

 cornis ; eighteen anemones (principally Mesembry- 

 anthemum) ; two pieces of deep-sea Tubularia gra- 

 cilis, upon which fine tentaculated heads have 

 developed ; a fine colony of Campanularia geniculata. 

 I may mention that I have kept the above-men- 

 tioned creatures for upwards of six months, and 

 some of them for a longer period, in the greatest 

 health. 



The expenses of this aquarium, with the neces- 

 sary paraphernalia, would be as follows : — 



5. d. 



The propagating-glass costs 7 



The gutta-percha tubing costs 3d. per 



foot, say three yards, at 9d 2 3 



The specific-gravity test costs 1 



The sea-water, Gd. per gallon, say six gal- 

 lons 3 



The tofal cost is 13 3 



So that for less than fourteen shillings I have an 

 unlimited amount of intellectual amusement and 



