as-filled tubes withreddish tinge, are the ones used, rather than themiliar greenish-light mercury-vapor tubes. An effec-ve use of them has been made in England. A longmnel with moving stairways and other passageways>nnecting an underground railroad station with thereet is lighted from end to…
Pottery · Glass · Glassware
Internet Archive · University of Illinois Urbana-Champaign · Public Domain Mark 1.0. Free to use for anything.
