Sunlight is part of everyday life and we accept it as good-and good it is in a number of ways. The sun is our source of warmth, and of the light by which we see. It is, in fact, the source of the energy with which life continues on earth. It furnishes energy for photosynthesis, and the pro- ducts of photosynthesis constitute our food, building materials, and fuel. A steady state of balance and fine interrelationships exists between life on earth and...