Complex sentence: In 1835 the society had grown to 1100 and in the early 1860s it had reached 1700 members, weekly sessions were held at Hotel Du Nord, then from 1826 at the Freemasons Hall, while the exhibitions were arranged at City Hall.
Split into simpler sentences: In 1835 the society had grown to 1,100 and in the early 1860s it had reached 1,700 members. Weekly sessions were held at Hotel Du Nord, then from 1826 at the Freemasons Hall, while the exhibitions were held at the City Hall.