An Ancient Means of Detection

● Electronic checking of airline passengers is common today. Its purpose is detection of armed would-be skyjackers. But the Chinese were using a similar means of detection some twenty-three centuries ago. At the imperial palace near Peiping, the Moon Gate was made of lodestone, which has magnetic properties that attracts iron. Why was this stone used? Says The Royal Bank of Canada Monthly Letter: “This was done to prevent assassins from entering the imperial residence carrying weapons concealed in their clothing.”