h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

*The lift is the only known access to the below-ground levels. It is operated by a security Ape, who must enter a code before the controls will work. The controls consist of a normal button panel for choosing the floor, and a spring-loaded lever which must be depressed for the lift to operate. The code must be entered on a small number panel before the lever can be depressed. The idea is that the security Ape keys in the code, then holds down the lever while the lift is in operation. If he lets go of the lever, it springs back to its upright position and then the code has to be reentered before it can be depressed again.*