On the night of February 20, 1838, one of the most dramatic and best-documented Spring Heeled Jack encounters took place at a house in Old Ford, in the Bow district of East London. Eighteen-year-old Jane Alsop answered a knock at the door to find a figure wearing a dark cloak who identified himself as a police officer and told her to bring a candle, saying 'we have caught Spring Heeled Jack here in the lane.' When Alsop brought a candle, the figure threw off his cloak to reveal tight-fitting clothing that appeared to be white oilskin. Most terrifyingly, the creature vomited blue and white flames from its mouth and had prominent, protruding eyes that 'resembled red balls of fire.' It attacked Alsop, tearing at her dress and hair with metallic claws. Her screams brought her sisters, who dragged her inside. The creature retreated and escaped. Jane Alsop's detailed testimony before magistrates, published in The Times and other newspapers, remains the most vivid firsthand account of a Spring Heeled Jack encounter. The descriptions of fire-breathing and glowing eyes suggest either elaborate theatrical effects or a genuinely inexplicable phenomenon.
