G'day Ray,

... Because it has nothing to do with a dance ... in 3/4 - or any other time signature! The expression ... here, in 19th century Australia ... comes from the German tradesman's time spent auf der walz ... "on the wander" for a number of years before advancing (on the strength of the experience gained over those years) towards "Master" status.

In this song, Paterson is putting the 'hard word' on Christina to go 'wandering' about Australia with him (despite the fact that he has been ... by that time ... engaged to one of her old school chums for seven years!

Regard(les)s,

Bob