A bill that carpenters Dinsmore and Neilson submitted for their work between 1809 and 1812 provided documentary evidence for the missing chimneypiece.  The bill included an individual listing of every chimneypiece they built for Montpelier.  Having the cost of each chimneypiece allowed the Restoration Team to compare how ornamental the existing chimneypieces were to how much they cost.  By extension, the team could then predict how ornamental any missing chimneypieces were.  For the North Wing Room the chimneypiece was found to cost £6 and that it was tied with the Jeffersonian chimneypiece in the Dining Room for the most expensive ca. 1812 chimneypiece.  The second most expensive chimneypiece was the Federal-style mantel found in the Large Bedroom that cost £5 8p.  Because the Large Bedroom's chimneypiece was in the Federal style, It would be this mantel that would serve as the major reference for the recreated chimneypiece in the North Wing Room.