56 THE MARINE AQUARIUM. 
CHAPTER II. 
FITTING UP—MATERIALS FOR THE BOTTOM. 
Coarse sea sand and pebbles, all well washed, make the 
best bottom ; but if sea sand is not to be conveniently 
obtained, common silver or gritty river sand will answer 
every purpose, if washed until they cease to stain the water. 
Most writers on aquaria—Mr. Gosse especially—condemn 
_ silver sand, but I find it a most suitable material: its 
appearance is cleanly, and it only requires frequent wash- 
ing in fresh water to fit it for the purpose. In the water- 
pipe which runs along the wall to supply the kitchen, 1 
have had a hole pierced to form a jet, and this I find of 
great service in many aquarian operations, and especially 
in washing sand and pebbles. Where this can be done 
conveniently, or where the pan containing the materials 
to be washed can be placed under a tap turned on so as 
to drip rapidly, the washing can be accomplished with 
very little trouble, and the materials can remain for a 
week or two, being stirred up occasionally to hasten the 
dissolution of solvent matters. The sand should have a 
depth of two or three inches on the floor of the vessel, 
and above it should be placed a layer of pebbles, also well 
washed, The little white pebbles found among gravel 
look bright and pretty, and if the aquarian is also a lover 
of the garden, he will turn up plenty of them in digging, 
so as to keep a supply at hand for use when wanted. 
The pebbles are not essential, but the sand is, because 
many of the creatures delight in burrowing, and must 
