In 1973 ours were very similar other than the two bolts securing each lamp cage had triangular heads and were individually shrouded requiring the use of a cheaply fabricated custom key to loosen and / or remove the bolts to replace the lamps.
The two keys originally provided were cast in white metal and soon cracked, failed, and became useless.
Post that, as lamps burnt out, we used pliers to remove the individual shrouds covering the bolts, then removed the bolts, and replaced them with Robertson head (Sculox within your walls) bolts. Most talent don't carry Red Robertson drivers, thus the cages were still unremovable for most talent.
Another thing we found, particularly with productions in for one or two weeks: When talent ran out of receptacles for their hair dryers and favorite accessories, some were removing lamps and replacing them with commercially made adapters to accept a single ungrounded
plug then adding a
power bar and after that folks kept right adding loads: Some bringing heating pads, toasters, coffee makers; small bar fridges, the variety was endless.
Originally one grounded duplex
receptacle had been provided between each pair of makeup mirrors in each of the 14 dressing rooms spanning the width of our
stage level U/S
crossover corridor.
One floor up we had four larger additional rooms intended to
house female and male chorus and female and male opera extras; supernumeraries.
These upper rooms were each equipped with ~six makeup stations.
Back at
stage level, immediately off S/R we had five dedicated "Star" rooms, each with private washrooms housing sinks, toilets, and showers. Each of the five "Star" rooms were designed to accommodate one or two stars touring with their significant others.
More than you NEVER wanted to know about dressing room lights in Hamilton, Ontario, in the fall of 1973.
Toodleoo!
Ron Hebbard