"Mercury arc rectifiers were invented by Peter Cooper Hewitt in 1902 and further developed throughout the 1920s and 1930s by researchers in both Europe and North America. Before the advent of solid-state devices, mercury arc rectifiers were one of the more efficient rectifiers. By 1975, high-voltage solid state devices such as the silicon diode and thyristor made the mercury arc rectifier obsolete even in high-voltage DC applications."
That picture certainly looks like what was in that room, and the dates hold out with the newspapers that were in there too - I wish i'd kept some of them. I always thought it looked like something out of Dr Who's Tardis, my memory may have been clouded somewhat in thinking it was a heating system as a voltage converter would seem more likely going by the responses on here. Anyway, a Mercury Ball, what a strange device and i've actually seen one. :shock:
I reckon you saw a mercury arc rectifier. It would have been installed when electric stage lighting was installed. The output could be controlled very easily for dimming and effects. Probably was not original with the theatre. I once saw a mercury arc rectifier running when I was an apprentice in the late 1970's. probably one of the last ones in regular use. it had to be viewed through a dark glass window in the cabinet. it was fantastic (well to me, anyway) .
I know it is going off topic for a moment, but I must say I am pleased that I was around as an apprentice and electrician to see the tail end of stuff like mercury arc rectification, Ward Leonard motor-generator sets and oil bath motor starters. All tose things are replaced today with a box that buzzes and has a cooling fan at the back...... but has no, well, soul.
I worked in a busy seaside theatre for six years as a sound engineer. It sure was a spooky place when you were in there on your own, especially in the auditorium which had a most unnerving atmosphere, and there were always rumours of a ghost - as in any theatre - but none of the people i worked with in there ever saw anything... i did... once.
We had Jim Davidson in on a three day run and he brought a big-ass PA system - a 5k rig - with him that had to be left set up in the theatre overnight. We'd had break ins around that time and it was required that a member of staff stay in the theatre overnight to watch the equipment and keep it safe from crims... I was that member of staff. I took some ribbing from the other guys and girls about getting spooked in the night or having to chase away crims but i wasn't fussed as i was the only one with the testicular prowess to actually stay the night and there was extra money in it for me.
Once everyone had left the building I walked the entire place turning off all the electrics, heaters and lights etc. I lowered the safety curtain in front of the stage and retreated to the bar area at the front of the theatre which was the only part of the whole place i was prepared to sleep in. The dim light from the glass-fronted beer coolers behind the bar was a nice comprimise between total darkness and having the lights blazing all night long. I guess it was around midnight. I picked a sofa next to the front doors and laid me down to sleep... after that things started getting weird.
Sometime later, it was still dark outside, i was woken by a loud banging sound close by to me. I sat up and both sets of swinging doors to the right and left of the bar area which lead to and from the auditorium were swinging violently and banging loudly, as if that wasn't scary enough i could see light behind the doors, light that appeared to be coming from the auditorium.
My heart was pounding as i crept across the bar and stedied the doors. Had someone broken in? I had to see, it was after all what i was there for.
I left the bar area heading to the main auditorium and passed the stairs that led to the upper seating tier, there was light pouring down the stairs. Then my heart skipped a beat as i heared the music coming from the auditorium. It was an out-of-tune piano that was playing some kind of music hall tune with a warbling, female falsetto accompliment and as you can imagine i was getting proper scared, but the worst was yet to come.
I had to check the main auditorium and the stage area so i headed to the last set of double doors that opened directly into the back row of seats on the ground level of the auditorium. There was definately music coming from the stage so i grabbed the door handle and was about to open it when the whole auitorium burst into applause and light cheers. My blood ran cold and i froze to the spot. Having worked in the place for years i knew what a full house sounded like and there was one behind the door i was about to open applauding a show in a theatre that was supposed to be as empty as it was when i locked the place down sometime before.
The applause went on as i slowly plucked up the courage to open the door. I managed to push it open about two or three inhes before my nerve gave out and i ran away, but i did see inside. There were two people on stage. A man in a black suit and a tall hat sat at an upight piano with both hands clasped to his chest in what i think is an old fashioned gesture of thanks. At the front of the stage was a women in a big scarlet dress with dark ringlet curly hair. She was bowing to the audience. I could only see a few seats through the gap but they were occupied. The nearest ones to the door i was peeking through were maybe five meters away and the only thing i can remember about their occupants was slicked hair and big hats That was it for me, i can't really convey how scared i was at that point and i think i may have weed myself a little, i ran out of there as fast as i could. As i ran back through the bar area i heared more applause and briefly wondered who had come though the bar area in the first place, banging the doors and waking me up. Oh yeah, i did see one other thing before i ran. We had gaslamps in the theatre. They were left over from victorian times and were very ornamental and sometimes quite a talking point. They were obviously redundant and had not been plumbed into the gas supply in god knows how many years, but in that auditorium on that night a phantom show was playing for a phantom audience and the gas lamps were burning brightly.
I ran home and didnt lock the front doors of the bar after me. I came back at first light. There had been no burglary thank god and the theatre was empty of all exept Jim Davidson's sound equipment. I told my dad who was the general manger at the time of my experience and he said that he'd heared some things from the previous owners about people hearing music in the place at night. No-one stayed to watch the gear the next night... least of all me. I've never been as scared as i was that night. The place has been demolished now and to be honest...i'm glad. This happened over 10 years ago.
One of the most astounding things about this thread IMHO is that it originated with the first hand account of a stunningly inexplicable paranormal experience, and is now zeroed in on the subject of mercury arc rectifiers.