Forward pressure sends the machine into the future. Backward pressure, into the past. And the harder the pressure, the faster the machine travels.
11 seconds sound clip from the The Time Machine (1960) movie soundboard.
You can hear this line at 00:12:21 in the Blu-ray version of the movie.
Quote context
[...]
- Wait, let's do this properly.
- You can spare a cigar, I trust, Doctor?
- Now, let us imagine that this cigar is the time traveler.
- Now, in front of him is the lever which controls movement.
[...]