This is from Temple Univ. Archeologist Dept.:
Sorry for my delayed response. The slipware mug is very intriguing. I consulted a a few other archaeologists and my advisor at Temple University about the mug, and they also found it to be very unique. Based on the picture, the mug itself does not appear to be from the revolutionary era. At the earliest it was likely produced in the mid-19th century. This is clear because the alley houses initially had a different numbering system starting at no. 1. Using the old system, I believe 139 Elfreth's Alley would have actually been no. 17. The new system was implemented in the mid-19th century; therefore the mug was almost certainty created after that time. Also, I am not familiar with any examples of individual potters writing an address on a slipware ceramic in the 18th century. Elfreth's Alley as a historic entity did not seem to enter the collective consciousness of Philadelphian's until the early 20th century. It seems unlikely that an early potter would specifically write out their location at Elfreth's Alley; it would be more probable that someone in the 20th century, familiar with the significance of the alley, would include this address. Additionally, while Slipware ceramics were produced in the 18th century, it appears that the handle to the mug may have been attached separately (difficult to see in photo); this would be uncommon for early ceramic pieces. Even if the mug is from a later historical period, however, it is still quite unique and valuable for the historical value it does have. As an archaeologists, we don't think of value in monetary terms, rather we think of what information an item can provide us and what we can learn from it. This mug is a physical symbol of Elfreth' Alley's past and its enduring tradition. I hoped that explanation helped you in your research. If there is any other information I can help with, please let me know.
I wrote back asking if he Cline family could be the owner's.
