possibly crack or scratch the glassy coating, such as pins, pennies,
pieces of wire, or slate pencils. It is best not even to try to bite
off threads or pieces of string. There is, of course, another reason
for not putting pencils and pennies and such things into your mouth:
they may have dirt, or germs, on them and infect you with disease or
at least upset your digestion.


II. THE LAND OF NOD

Now you are all ready for bed; and the white pillow and the nice,
clean sheets and the warm blankets look very good to you, and you are
ready to go to the "Land of Nod."

You need not be afraid of the cold at night. Open your bedroom
windows. Have plenty of light-weight, warm covers; then the cold
breezes won't hurt you, but will make you strong. Just think how many
hours you are in bed,--nearly half of your life,--and you need fresh,
moving air all the time. Be sure to open your windows from the top as
well as from the bottom. You know why: your breath is warm so that it
floats and rises like smoke; and if you open the window only at the
bottom, this bad air, which rises to the top of the room, can't get
out. It is best to have windows on two sides of a bedroom, so that the
air can be kept moving through it all night long. If you don't breathe
fresh air while you sleep, you will feel dull and stupid in the
morning and perhaps have a headache.

So run your window shades right up to the top and throw your curtains,
or shutters, back, as well as open the windows. If you don't, the
fresh air cannot blow through the room properly. Even if this does let