7 The 100 Most Influential Inventors of All Time 71751 the Academy of Philadelphia, from which grew the
University of Pennsylvania, was founded. He also became
an enthusiastic member of the Freemasons and promoted
their “enlightened” causes.
Although still a tradesman, he was picking up some
political offices. He became clerk of the Pennsylvania
legislature in 1736 and postmaster of Philadelphia in
- Prior to 1748, though, his most important political
service was his part in organizing a militia for the defense
of the colony against possible invasion by the French
and the Spaniards, whose privateers were operating in
the Delaware River.
In 1748 Franklin, at age 42, had become wealthy enough
to retire from active business. He took off his leather
apron and became a gentleman, a distinctive status in the
18th century. Since no busy artisan could be a gentleman,
Franklin never again worked as a printer; instead, he
became a silent partner in the printing firm of Franklin
and Hall, realizing in the next 18 years an average profit of
over £600 annually. He announced his new status as a
gentleman by having his portrait painted in a velvet coat
and a brown wig; he also acquired a coat of arms, bought
several slaves, and moved to a new and more spacious
house in “a more quiet Part of the Town.” Most important,
as a gentleman and “master of [his] own time,” he decided
to do what other gentlemen did—engage in what he
termed “Philosophical Studies and Amusements.”
Scientific Studies
In the 1740s electricity was one of these curious amuse-
ments. It was introduced to Philadelphians by an electrical
machine sent to the Library Company by one of Franklin’s
English correspondents. In the winter of 1746 –47, Franklin
and three of his friends began to investigate electrical