Evidence that the Central Pacific did at least try power drills in Summit Tunnel. I wonder what patents the drills were built under.
Summit Tunnel – Air Drills in 1867
April 1, 1867 – San Francisco Alta Californian – from GM Best notes
Central Pacific – Summit Tunnel
Vulcan Iron works built "atmospheric drilling machines", four of which were used by the Central Pacific in Summit Tunnel.
Drilled 1 1/2" holes for nitro-glycerin.
Drilled at rate of 1 1/2" per minute.
Air supplied by air pump – steam powered - on surface.
Air pressure 20 lbs.