I seem to vaguely remember reading about a train that used air pressure difference in a tunnel, similar to Hyperloop but at much lower speeds back in Victorian times. IIRC it sucked air at one end to draw the carriage along, which had big rubber seals that moved along the tunnel walls. I've no idea if that was just a concept or if any form of test line was ever built though. It may be that it was an earl;y idea that that never got built but led to the atmospheric railway.
Biting the hand that feeds IT
