Once, as he was walking with a colleague, Donald MacDougall, he saw a poster that admonished, “Stop that dripping tap,” an exhortation meant to conserve water and thereby save the coal that fueled the water-distribution system. As he walked, the Prof began calculating the costs in energy, wood pulp, and shipping needed to produce the paper for the posters. “And of course,” MacDougall recalled, “Prof was right in his initial suspicions that it all added up to enormously more than was going to be saved by the posters’ advice being followed.”
