Reading a pressuretrol--dumb question?

This may be a dumb question--but where dors the dial read the "Cut-out" differential on the standard little gray Honeywell Pressuretrol, like the one pictured in "We've Got Steam Heat"? It's actually not clear where the "1" should be aligned at for a 1 pound differential, and of course I have no owner's manual.
If you can relate the answer to that photo, which has an arrow that may or may not mean this is the spot to measure pressure, that would probably make the answer clearer.
Thanks