The top is brass, as you can see in photo 4 the brass thread has become a little misshaped over the years. This could easily be upcycled into a fabulous standard lamp.
Apologies for the postal cost, this is high because of the length of this piece. The item "Antique Vintage Wooden & Brass Large Surveyors Theodolite Tripod ideal lamp" is in sale since Monday, May 7, 2018. This item is in the category "Collectables\Scientific Collectables\Engineering & Surveying". The seller is "pennylanevintageretro" and is located in Mareham Le Fen, Lincolnshire.This item can be shipped to United Kingdom, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Australia, United States, Canada, Brazil, Japan, New Zealand, Israel, Hong Kong, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Switzerland, Taiwan, Thailand, Saudi arabia, South africa, United arab emirates, Chile.