What is quite so wretched looking as a wet hen ? She is drenched by a hard rain just as quickly as you are. But you never saw a wet duck, did you? Yet a duck spends most of its life swimming in ponds. It dives for food and comes up as dry as bone. The feathers do not account for this, for the duck's feathers are not so very different from the chicken's. The secret of it is that the duck's feathers are oiled. There is an oil-making gland on the duck's back near the tail. The duck spreads a film of this oil all over the surface of its feathers. Now oil and water will not mix, so the water cannot get through this oil to wet the duck's feathers. Besides, the oil slips past the water, making swimming easier. The next time you go swimming oil your back and the water will roll from it just as it does from a duck's back.