Nobody knows for sure ...

... what Bourdin was trying to do that day. An investigation showed that he was closely linked to anarchist groups. Numerous theories circulated: that he was testing the bomb in the park for a future attack on a public place or was delivering it to someone else. But because he had primed the device and was walking the zigzagged path, many people — including the Home Office explosives expert, Vivian Dering Majendie, and the novelist Joseph Conrad, who loosely based his book “The Secret Agent” on the event — suspected that Bourdin had wanted to attack the Observatory.