From 1883 to 1904 scientists lived and worked year round at the summit of Ben Nevis - observing the weather at 1,343metres (4,409 feet) above sea level was an extreme task. This images shows the Observatory iced up in the winter. The snow was often so deep that it buried the lower doorway. The tower exit ensured that the observers could continue making observations when the lower doorway was iced shut or buried in snow. In very high winds the men had to tie themselves to the building to avoid being blown off the cliff! This photograph shows an observer working on the roof of the observatory in winter.