CAGE AND SINCING BIRDS. 
13 
iiiglit, and thus give additional security to tlie birds, sliding- 
flutters of wood migiit be fitted to the interior, and 
drawn backwards and forwards at pleasure. Spaces like 
windows should be left free from glass, and covered only 
with a network of wire, through which the captives could 
communicate with their friends at liberty, for whose accom- 
modation a ledge should be fixed outside the wmdow. The 
removal of the warblers into the inner and warmer compart- 
ment should generally take place in August, shortly before 
the period of migration, at which time the majority of birds 
in confinement manifest an extraordinary degree of agitation, 
frequently stretching their wings and endeavouring to soar 
upward, and sometimes kilHng themselves in their efforts 
to effect their escape. It is best, then, to keep them in 
cages darkened and miiSled, so that they cannot hurt them- 
selves. 
So exceedingly sensitive are the lungs of the feathered song- 
sters, that a very slight impurity of the air, especially when the 
temperature is at all varied, will suffice to cause them great 
uneasiness, if not actual stoppage of the respiratory organs ; 
therefore it is not safe to introduce into the aviary any close 
stove 4'om which carbonic acid or other noxious gas could 
arise. It is best to have the warm air conducted in pipes 
from some adjoining building, where there is an open stove. 
•Great care should be taken, too, in SAveeping or cleansing to 
avoid raising much dust, and to exclude damp and fog, espe- 
■cially from the warblers. Kidd recommends that the foun- 
tain should be of zinc, about eighteen inches in circumference, 
with a turn-over top, and sides gradually shelving downwards 
to the depth of about four inches, with a pipe to carry off 
the waste and foul water below, and one leading from a 
€istern above to supply the fresh, so that the birds can stand 
under it on pieces of coral, stone, or crystal rock, and per- 
form their ablutions, which they do with great regularity and 
•apparent pleasure. This authority also directs that the 
hoppers or food troughs shall be made of mahogany, on the 
principle of a rack, having a moveable slide of transparent 
glass in front, and a lid with hinges at the top. All along 
the front of these hoppers there must be a projecting ledge, 
or rail, on which the birds sit while feeding, and underneath 
round holes through which they put their heads to obtain 
