Another library gem:

That's from the 1914 book "The Climatic Factor As Illustrated in Arid America". The analysis that goes with the graph seems, with our centuries' worth of hindsight, a bit naive. The argument is that when it rains too much in Europe, crops fail, so people move to America. The link between climate and human culture is more complicated than the graph's neat correlation would indicate. But what's so amazing is not that the author was simplistically wrong, but that he was posing these great, penetrating questions that rightly supposed that the climate-culture link would be huge and important and worth our time.