PROBLEMS
1. Why should we have the outside of a tea-kettle, teapot, or hot-air shaft of a bright colour? Why should we have stoves and stove-pipes dull black?
2. Why does a coat of snow keep the earth warm?
3. Which is the warmest colour to wear in winter? Does this account for the colour of Arctic animals?
4. Which is the coolest colour to wear in the hot sun?
5. Gardeners sometimes strew the ground with coal-dust to help ripen their melons. Show the value of this.
6. Suggest a method of protecting a wall from the heat of a stove.