The pitch, a derivative of tar once used for waterproofing boats, is so slow that a grand total of only eight drops have been produced since the stem of the funnel was cut in 1930. The drops fell in 1938, 1947, 1954, 1962, 1970, 1979, 1988 and 2000. Unfortunately, no one involved with the study has seen a drop in action, including Professor John Mainstone, who has run what is thought to be the world's oldest laboratory experiment since 1961.
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