In 1856, Rowbotham married for a second time and had two children, one of whom died in infancy. In fact, only half the lantern was visible, yet Rowbotham claimed his opponents were wrong and that it proved the Earth was indeed flat so that many Plymouth folk left the Hoe agreeing that "some of the most important conclusions of modern astronomy had been seriously invalidated". His opponents had claimed that only the lantern of the Eddystone Lighthouse, some 14 miles out to sea, would be visible. Proctor, a writer on astronomy, and proceeded to the beach where a telescope had been set up.
When finally pinned down to a challenge in Plymouth in 1864 by allegations that he wouldn't agree to a test, Rowbotham appeared on Plymouth Hoe at the appointed time, witnessed by Richard A. However, as he persisted in filling halls by charging sixpence a lecture, his quick-wittedness and debating skills were honed so much that he could "counter every argument with ingenuity, wit and consummate skill". He took a little time to learn his trade, running away from a lecture in Blackburn when he couldn't explain why the hulls of ships disappeared before their masts when sailing out to sea. After measuring a lack of curvature on the long straight drainage ditches of the Bedford Levels in his first Bedford Level experiment, he was convinced of the flatness of the Earth and began to lecture on the topic. Rowbotham started out as an organiser of an Owenite commune in The Fens, where he formulated his ideas about the Earth.