From Discworld MUD Wiki
Journey is a command you can use in the terrains to move several rooms instead of just one.
On a road you will follow the road. This means if you
journey east you might be facing any direction afterwards, since the road can turn a lot.
Elsewhere, you will move in the given direction. Sometimes you cannot journey in a direction because the terrain type changes, then just move a couple of times in the direction and you should be able to journey again, unless there's special rooms or another change.
You can also journey while mounted to automatically continue to journey until you stop or cannot proceed further.