Betula pubescens planted trees, while naturally regenerated trees seem less susceptible. This disease also affects "Betula pendula" and in 2000 was reported at many of the sites planted with birch in Scotland during the 1990s. The outer layer of bark can be stripped off the tree without killing it and can be used to make canoe skins, drinking vessels and roofing tiles. The inner bark can be used for the production of rope and for making a form of oiled paper. This bark is also rich in tannin and has been used as a brown dye and as a preservative. The bark
Northern celestial hemisphere Northern celestial hemisphere The northern celestial hemisphere, also called the Northern Sky, is the northern half of the celestial sphere; that is, it lies north of the celestial equator. This arbitrary sphere appears to rotate westward around a polar axis due to Earth's rotation. At any given time, the entire Northern Sky is visible from the geographic North Pole, while less of this hemisphere is visible the further south the observer is located. The southern counterpart is the southern celestial hemisphere. In the context of astronomical discussions or writing about celestial cartography, this celestial hemisphere may also simply then be