The only maker's mark on the lamp I can see is on one of the bottom panels of the outside of the shade, the initials "P H" appear with a large space between the two letters. If you do an internet search with his name, you can find several slag glass lamps done by him that bear the same "P H" maker's mark. There was some information on the old socket, but I think it was just the socket maker, and it has since been replaced with a new one.
The lamp features a cherub figure done in the Art Nouveau style. This lamp is about 22 inches tall with the shade on it. The base of lamp has a square that is about 7.5 x 7.5 inches. The shade is very heavy. It is made of 6 panels of green stained/slag glass that form an umbrella shape, it is very heavy, but light still passes through it very nicely.It measures about 12 inches in diameter and it is about 7.5 inches tall. This lamp weighs a total of just under 12 pounds. When I found this lamp, the socket did not work so I took it to a lamp shop and had the socket replaced, the cord is still the same and is definitely an older cord. The lamp works now just as it should. It has a slide mechanism to turn it on or off. There is a finial on the top that you remove by screwing it off and then you have access to remove the shade. The shade support is also removable by pinching the two sides and it comes out of the groove by design. Condition - It is pre-owned and well used. The metal parts of the base and shade have oxidation and discoloration but that definitely adds a nice patina to the piece.
The inner glass is intact, there could be a few small flea bites where the glass jostles around because it is just held in place by metal prongs. The lamp works, as stated the socket is new, but the cord was left because I wanted to leave the lamp as original as possible.
As far as the age of the piece, I really have no idea, my research has come up empty. If you search for "P H Lamp" I get lots of possibilities but I can't be sure so I will leave that up to the experts out there. It really is a beautiful lamp, and if nothing else, its definitely aesthetically pleasing to look at.Please look at all the photos to gain an idea of the condition of this item for yourself. I will double box it and wrap securely for safe travels. The item "Antique Vintage Art Nouveau Stained Slag Glass Table Lamp & Shade Poul Hornison" is in sale since Saturday, March 23, 2019. This item is in the category "Antiques\Decorative Arts\Lamps". The seller is "aaron497" and is located in Myrtle Beach, South Carolina. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, South africa, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia, Brazil, Chile, Colombia, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bangladesh, Bermuda, Brunei darussalam, Bolivia, Ecuador, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Peru, Pakistan, Paraguay, Reunion, Viet nam, Uruguay.