Book review Spirits from the sky

Archaeologists took a great leap forward in understanding the past as soon as they were able to look at the Earth from the air: for the first time, they could map the overall design of ruinous sites, establish connections between apparently diverse details, and see the relationship between buildings and the natural environment. The first significant breakthrough was made in 1906 by PH Sharpe, who snapped Stonehenge from a war balloon during an exercise flight. By the late 1930s, and thanks to better cameras, let alone more reliable aircraft, Osbert Guy Crawford, who is generally described as the inventor of aerial photography in archaeology, had developed methods of producing and analysing the results which have stayed pretty much the same ever since. He realised that it was sensible to work at times of day when the angle of sunlight showed other-wise hidden elements, he was able to understand the patterns created by lighter and darker patches of vegetation, and he began to reconstruct ancient farming systems as well as town-scapes. "Aerial photography," he said in 1938, "has provided archaeology with a research tool that is as valuable to it as the telescope was for astronomy."