On 30 June 1859 Charles Blondin successfully crossed the 340 metre span of the Niagara gorge on a tightrope suspended 50 metres above the rushing water. As if this wasn’t enough, he repeated the feat several times over the next few months with some added twists: he crossed on stilts, he crossed blindfolded, he carried a stove across and made an omelette on it, and then he pushed a wheelbarrow across. On reaching the other side he apparently asked the rapturous crowd whether they believed he could push a man across in the wheelbarrow. Their affirmative cheers drowned out the roaring river, but when he asked for a volunteer they fell silent ...