Dating Clay Pipe Stems:
Clay, or kaolin, pipe stems look a bit like narrow white tree branches with holes down their centers. According to an article by Maj. Robert J. Dalessandro, pipe stems were the “17th, 18th, and 19th century equivalent of the cigarette butt”. Clay pipes had very long stems and as the stems became clogged, the ends would be broken off and discarded. It’s not uncommon to find these discarded pipe stems, but it wasn’t until excavations at Jamestown in the early 1950s that archaeologists began realizing that these discarded stems could help them date a site. J. C. Harrington, an archaeologist with the National Park Service, studied hundreds of dated pipes and realized that the stem’s bore diameters directly related to certain time periods. These are the guidelines Harrington determined:
You can determine the approximate dates of pipe stems you find like this: carefully clean the stem, removing dirt from the hole. Gently insert the back end (end that goes into the drill) of the drill bits of the sizes mentioned above into the hole – the one that fits snugly gives you the size of the bore, which you can then match to a specific period.
The Sivilich Formula:
Use this Excel file calculator to determine the diameter of an impacted or deformed musket ball: