Andy is right again.
If the conductor's head is over the backrest of his seat you are on ascending grade. If the head is tilted forward with the chin on the chest, then you're going down hill.
At times he handles the radio as well, as in the following example:
"Dispatcher X to conductor Y on the 2644 North, over."
"Conductor Y, 2644 North, over."
"What time will you reach point Z, over."
Conductor turns to engineer and asks, "What time will we be a point Z?"
Engineer says, "01:30."
Conductor calls dispatcher, "Dispatcher, we'll be there at 01:30, over."
"Ok. Dispatcher X out."
"Conductor Y out."
Then conductor goes back into incline-o-meter mode.
And speaking comparatively, it should be noted that freight conductors are different from a puppy only in that the puppy quits whining after a few weeks...