💙 Is it really #BlueMonday if blue is your favourite colour? These two hazy cyanotype photographs of London, overlooking the River Thames, were likely taken in the late 19th century. The distinctive blue of a cyanotype results from its exposure to ultraviolet light. The cyanotype photographic process was invented by Sir John Herschel in 1842, as a means to reproduce his mathematical thinking. English watercolourist and botanist Anna Atkins used this new process to capture algae specimens, laying her specimens directly upon photosensitive paper, and as such is considered to be the first woman photographer. 💦 View from the Thames, Unknown Artist ⛵ By the Thames, Unknown Artist