VENTILATION. 
171 
to expand and to become lighter. Then, of course, 
the warm air rises. At the same time the cooler 
and heavier air from over the sea rushes in to take 
its place, and thus we get a sea-breeze. 
8. During the night the land gives up its heat 
more quickly than does the sea, until it becomes 
the cooler of the two. Then the colder air moves 
outwards from the land to the sea, taking the place 
Diagram illustrating Lanrl-breeze. 
of the warmer and lighter air that rises over the 
water. And in that way a land - breeze is produced. 
9 . Taking the breezes at Kingston as an example, 
we find that a northerly wind blows there at night 
from the land; and, as the day advances and the 
land becomes heated, this gives place to a south or 
south-east wind from the sea. 
VENTILATION. 
l. The air that a person breathes out from his 
lungs is very different from that which he takes 
