My Collection: Thorn Gamma 9

With thanks to Lichfield Council for giving me permission to save this lantern, and collector AgentHalogen_87 for helping me obtain it. This lantern is the prize of my collection, and probably the rarest asset in it. I had vowed to rescue it since I knew of its existence, and the fact it had been disconnected from mains supply for two decades, meant it was essentially sitting and waiting for its demise at the hands of vandalism. Although it took over one year to get formal permission to rescue it, it was well worth the wait!

The lid of the lantern is held on via an aluminium cap, which can be unscrewed and removed in its entirety. Surprisingly, despite the corrosion present on this example, all screws except the wire clamp screws turn freely - even the grub-screws!

The cover is held together at the base by a length of insulation tape but despite this, it is complete.

Unlike the Gamma 6, or fluorescent Gamma 9, the mounting apparatus in these is recessed into the lantern itself, and the grub-screws are located inside.

Unscrewing the cap mentioned before allows the inside of the lantern to be accessed.

The lanterns hat is quite a bit thinner than the Gamma 6s, but bears a similar design. Both would have been black originally, but most of the Gamma 9s paint has been eroded away.

Inside the lantern is a rare 160W self-ballasted mercury lamp. These were not an option with the Gamma 9, so this example was likely GLS or SOX originally, before, on the 13th November 1998, a self-ballast mercury lamp was installed. I'm leaning towards it having been a SOX example, as the remains of a lamp-support can be found inside, as well as the known presence of an AC Ford box on the bridge this came from, which was removed in more recent years. My guess is both the SOX lamp and it's gear was rescued, and the mercury lamp was installed as a replacement. I do wonder if it's gear and lamp are still out there today. These self-ballasted mercury lamps can get very, very hot, so despite me switching it on once, I won't be running it in this lantern due to fears of damaging the cover. I will likely install a SOX or GLS lamp instead.

The bowl has ridges on the inside which act as refractors.

With the lid and cover removed, the Gamma 9's simple structure is obvious. Essentially, this version of the Gamma 9 is just a tube with a lamp inside.

An exact date is present on the lamp's base, as well as Phil Hallam (another collector's) signature. I do genuinely wonder if this lamp has ever worked in service, but I'd guess it hasn't, or didn't for very long.

The sticker inside is heavily faded, and very crispy. Great care was taken when cleaning the lantern as to not damage the sticker anymore. I did manage to reconstruct this sticker, with the minor blunder of misreading the 60W SOX as 50W SOX, and the correction can be seen on the new sticker!

The Gamma 9 lit with it's 160W self-ballasted mercury lamp.