From the George Washington Foundation:
Find one and suddenly you find them all. Two weeks ago we shared a rarity for us in the form of a complete tobacco pipe bowl with a maker’s mark. Well, we have found another one in the same feature.
While this bowl is broken, it still bears the “TD” mark and falls into the mid 1750s-1770s range. Some slight difference exist between the two bowls though as this one appears slightly smaller, the letters are spaced further apart, and the mark is not as well defined. We have a little over a week to go. What do you think we will find next?
