In 1907 and 1908, the US Senate bought Paul Wirt pens. Based on digitized files, it is not clear if these were bought other years as well. I was only able to find digitized references in the 1908 Senate expenditures. There is mention of the House of Representative buying Wirt pens in 1911, but I have not seen pens marked as such. Please check out the Wirt Nibs page for size comparison. A period catalog lists #8 nibs, but not a model number for the pen holder.