Equivalent to 'Gap before Bar'

[Marc Schonbrun]

Hello,

One element that I use quite often in Sibelius is 'Gap before Bar', which, 
unsurprisingly, places a gap before the bar you've selected. It's wonderful for 
writing books and examples where you want to have two columns of equally spaced 
single measures. What's the easiest way to do this in Lilypond? I know that I 
can just do a blank measure between the two measures I'd like to use, but I was 
wondering if Lilypond has an equivalent property for creating a user-defined 
space between measures. I've looked in the documentation, but didn't easily 
find the answer. 

Thanks,
Marc