Houdini fired a pistol in the air and--poof!--Jennie was gone.

The Hippodrome was a large-scale Manhattan entertainment venue that struggled mightily to make money in its later life, finally closing in 1939. But it had some great moments during its glory years. One such sensation was the time in 1918 when Harry Houdini made Jennie, a several-ton elephant, vanish into thin air in front of a 5,000 awed patrons. How did he do it? Mirrors. A 2007 Daily Mail article recalls the spectacular moment and its backstory. An excerpt:

“‘Ladies and gentlemen,’ Houdini cried as, to the audience’s alarm, a full-grown Asian elephant, 8ft tall and weighing over 6,000lb, came running pacily into view. ‘Allow me to introduce Jennie, the world’s only vanishing elephant.’

Jennie the elephant proudly raised her trunk in greeting to the wide-eyed masses, before being led into a huge, brightly coloured box on wheels. The doors were closed behind her, there was a dramatic drum roll and the stage hands flung open the doors at both ends of the box to reveal that it was now – completely empty.

Houdini announced to rapturous applause: ‘You can plainly see, the animal is completely gone.’

The Vanishing Elephant became one of Houdini’s most famous tricks and he performed it in front of over a million people. For more than 90 years, long after his death, the tradecraft by which he made this huge beast disappear remained a secret even other magicians failed to solve.”