The engraved four clasped hands are the logo of the Philadelphia Contributionship for the Insurance of Houses from Loss by Fire. This was the first American insurance company, founded in 1752 by Benjamin Franklin. Franklin also established a private fire department to protect the buildings his company insured. A metal plaque formed as four clasped hands was nailed onto each building the company protected. These "plaques" became known as "fire marks". The company has been in continuous operation for 245 years, under the same name.
Samuel Sansom was the treasurer of the Philadelphia Contributionship for the Insurance of Houses from Loss by Fire from 1807-1817.