49 C.F.R. § 230.56 Water glass lamps.
Title 49 - Transportation
All water glasses must be supplied with a suitable lamp properly located to enable the engine crew to easily see the water in the glass.
Title 49: Transportation
PART 230—STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS
Subpart B—Boilers and Appurtenances
Water Glasses and Gauge Cocks
§ 230.56 Water glass lamps.
