Thanks Silverliner!
I knew that the first answer was not correct for the base of the lamp and. I decided to wait from my colleagues for the correct and more detailed answer!
I have been collecting lamps since 1984. Here is part of my collection:
http://ixbt.photo/?id=user:1004332 I'm sorry there is no at this point in time to start posting photos of my lamps on this forum.
Thank!