634 R. M. STRONG 
The dimensions given above were chosen mainly in order that 
the apparatus might be accommodated to the size of the room 
available for the experiments, and they seemed to be suitable 
for the work with ring doves as the experiments proceeded. 
ue 
' 
/ 
Cc. 
Text fig. B Labyrinth with cover (c) in place; /, funnel of exhaust; p, Richard’s 
air pump (two air pumps were used at this point in the oil of bergamot series). 
The control of air currents naturally demanded an indoor location 
for the apparatus. 
In order to reduce the danger of general diffusion of the odor, 
an air exhaust was arranged. A funnel with a diameter of 64 
inches at the larger end was mounted with the small end up at 
the center of the cover to the main enclosure, and this was con- 
nected with a Richards? air pump which was attached to a water 
* During most of the experiments with oil of bergamot, two of these pumps 
were used with a T connection in order to accelerate the removal of diffused odor 
from the central enclosure. 
