136 Song .Birds. 



better to omit the directed rise of tiro inches in the- 

 middle, and substitute for it the same rule applied to. 

 a slight slope from the hack to the front) ; " over this- 

 lay half an inch of gravel and lime or fine chalk ; 

 water, and roll well again." We may, or may not go- 

 on to add one eighth of an inch of the best coloured 

 gravel, and again to roll until it is quite solid. The 

 lime and gravel is, however, about the best thing birds 

 can have to peck at. 



6. It is another good plan, as I have already 

 Muted, to have two sets of trees, and to turn out one 

 row at a time to get the benefit of a few showers, 

 whenever there are no nests actually in progress in 

 their branches; always remembering, however, that 

 the last shower had better be an artificial one, as 

 London rain has not the most cleansing qualities. 

 These trees require a good deal of water always, at 

 any rate at the roots and the thicker they stand to- 

 gether, the better the birds will like it when they are- 

 looking out for an attractive spot for nests. 



The floor should be covered at least four inches 

 deep with sand, and I think the best way is then to 

 clean it out occasionally from the outside with a thing; 

 like a hoe, having first removed the plant shelf to 

 render it accessible. The plant shelf, I ought to have 

 said before, should be in fact a deep box along the 

 front wall, filled nearly full of pieces of broken 

 charcoal, with the top only covered with sand, and a 



