You may note that there are a lot of "unknowns" in there.  The main reason for that is that the lamp you see here spent many years in a street light near here, which had long, long since lost its weatherproofing rubber seal - as a result half the lamp was immersed in water - the half which had originally the stamp on it.  So, I have no model number, no date code, no nothing.  Luckily I can tell from the tube structure that it's an Osram product.

You may also note that there's tape wrapped around the neck of this lamp.  The reason that's there is quite simple, and that reason is that the outer envelope of this lamp is cracked.  Quite how that happened I have no idea, I know it happened in the middle of the night, when the lamp was sitting on the desk in here.  I woke up at about four in the morning hearing this "clinking" noise coming from the desk, I turned on the lights, went over, and got there just in time to see the whole outer envelope part company with the base about 10mm up from the clamp.  I crudely taped the thing back together so as to minimise the chances of the inner tube becoming broken.  I may clean it up and glue it back together some day for the sake of cosmetics, then retake the photographs. 

Despite having no vacuum in the outer jacket, the lamp does still operate, and still manages about 85% of its full output, though it does never quite run up fully now.  Obviously, running like that is hard on the lamp electrodes though, so it would probably have failed prematurely if still in situ in this condition.

This was one of three lamps which were my first low pressure sodium examples.  Rescued from an almost certain trip to a skip after some SOX streetlights in a local village were replaced with fluorescent versions (a bad thing I think).  The workman there donated me two fixtures and a random lamp (this one).  Both fixtures contained 35W SOX lamps, one nearly new, one expired.  The working SOX lamp is with a friend just now who has borrowed it to find out whether an SO fixture outside his hotel works or not.  I shall add it here when it is returned.

If you can tell me from the images here what the production date of this lamp is, or can point me towards any details of its electrical characteristics I would be most grateful.  This is a technology I'm still very much learning my way around!