140 THE KITCHEN-GARDEN. [chap. vi. 
the largest pieces are thrown in first, then 
smaller ones, and lastly pieces broken very 
small, which are rammed down, or rolled, so 
as to form a smooth surface immediately 
under the gravel. This is done both to give 
solidity to the walk, and to prevent the 
gravel from being wasted by trickling down 
between the interstices of the stones. As 
walks can never be firm unless they are kept 
quite dry, in all cases there should be at 
least one drain to each walk. The gravel 
before laying down should be sifted, and all 
stones, larger than a moderate-sized goose¬ 
berry, should be thrown out or broken ; and 
as soon as it is laid down and evenly spread, it 
should be well rolled, previously to which, if 
it should be very dry, it ought to be sprinkled 
with water. If the gravel be at all loose, it 
should be mixed with equal parts of brick- 
dust and Roman cement before laying it 
down; or the gravel should be mixed with 
burnt clay powdered, in the proportion of one 
wheelbarrow full of clay, to a two-horse cart¬ 
load of gravel; or if the gravel be already 
laid, and it is wished to render the walk 
more firm, powdered burnt clay may be 
