With some great photos and references for those who want to read more. Thanks to Per Storemyr for sending me the link.
Historic photos are essential for research on monument weathering. With free internet access to archives, such photos are now easier to find than previously. In this article, I will show the case of Cleopatra’s Needle, a famous Ancient Egyptian obelisk transferred to New York in 1880. Its severe weathering occupied Erhard Winkler, a pioneer on the historic implications of monument weathering. But Winkler overlooked a key historic photo that would have seriously altered his interpretations.