De Booys was granted permission to build a windmill to produce cement, paint, and tanbark. Lawful or otherwise exchanges also took place with the Channel Islands (tanbark, grain and wool). In Europe, oak is a common source of tanbark. The tanbark was loaded by cable onto waiting vessels anchored offshore. A great quantity of tanbark is required, around 2,880 litres for 150 hides. Characteristic species include coastal redwood, California bay, tanbark oak, big-leaf maple, and western sword fern. Tanbark is the bark of certain species of trees. Tanbark oak, California laurel, sugar pine, madrona, broad-leaved maple, and Douglas-fir also grow here.