The opening of the episode returns to Philadelphia where the Reverend, using an orrery, lectures on the Transit of Venus and the solar parallax. In Cape Town, the skies clear long enough for Mason and Dixon to take their observations. A strange lassitude descends on the colony for several weeks after the event but normal routines are soon restored, even as the Vroom daughters find new objects for their attentions. After several months, Mason and Dixon depart Cape Town aboard HMS "Mercury". The Reverend closes the episode by musing whether something other than philosophical or scientific desire drives astronomers worldwide to their observations.