This oven could cook a 12 pound turkey in 4 to 5 hours. This is still a popular design today. We actually use a large model, very similar to Adam's oven. We feel a new awareness is blooming. Solar cooking enables us to contribute in a small, simple way.
Sunlight is concentrated in a cooking area by using mirrors or any reflective surface.
Consider a car parked in the sun with all the windows up. The sunlight is absorbed as heat by the car's interior. The rolled up windows help keep the heat and hot air within the car. In solar oven heat is captured inside an enclosed area and is absorbed by the food and pots or pans. This is called the greenhouse effect and applies to cars, solar cookers and planets.