oil lamp, hall/trade mark? stamped "porto"

[Jaygo]

Hello. I am a chance visitor trying to identify a stamp on an oil lamp recently purchased from Portugal. It was advertised as "chrome plated" but I seriously doubt that. I would have said nickel as that was a typical finish but, it doesn't have that nickel shine and I have never seen such stamps on the bottom of a chromed or nickeled piece before.
I have googled Portuguese silver hallmarks and it is certainly not one I saw provided. I suppose it could be a company or trader's trademark?
Anyway, it's a Kosmo type burner oil lamp. I am getting it from Portugal and the "porto" stamp would seem to suggest it originated there but, there is no guarantee of that I suppose.
I bought this for my collection. I am not interested in values or selling or anything like that. I just want to know about this lamp!
Here are the images. They seem to work all right in 'preview so I hope all is well.

[Jaygo]

Hello all. I see many have viewed this but none have had a reply. It's been awhile so I thought I'd give one more run at it.

Lets try a different tack. If nobody recognizes this 'stamp,' maybe someone can suggest a place where I might research it. For the record, I have made attempts to find out something on my own. But, what I ran into was the problem that "crown" and "Porto" are such common search terms that I get so flooded with responses that I get overwhelmed wading through them. I hope somebody can make some suggestions that could narrow down my search. I assure you, it would be very much appreciated for whatever that may be worth.

And, it's not about money because this is of no real great value. I'm just plain curious. I like to know all I can find out about such things. Actually, I bought this lamp primarily for light in emergencies or hard times and also because it fits nicely in my little hodgepodge 'collection' of lamps. The beauty of the Kosmos burner is that it averages smaller and delivers more light for less oil than the same size wick would in a flat wick burner. They tend to give brighter light than other similarly sized lamps because they work something like center draft lamps...
ahhh...
Sorry for going on. I realize this isn't a lamp forum. But having typed all this, I'm going to leave it. Maybe somebody will find it of interest and some maybe even useful.

Anyway, again, any help will be appreciated.
Thanks

[AG2012]

Hi,
There seems to be no controversy here;Kosmos burner was developed (invented) by Wild & Wessel of Berlin in 1865 (wick "Goes in flat, comes out round").Exported and patented worldwide,Portugal included.
Local manufacturer in Porto built in German burner and added his stamp.It seems there were letters above the crown in partially printed mark;possibly the name of the manufacturer.
Regards