What is the significance of Wemmick's museum in Great Expectations?

In Great Expectations, as in many of
his other novels, Charles Dickens delights in creating humorous and whimsical characters
with odd names.  Wemmick is such a whimsical character, although at first he does not
seem so as he is cryptic in the office of Mr. Jaggers as he speaks with his "post
office" mouth that merely takes in information and sends it out without any of his own
personality being revealed.

However, when Pip is invited by
Wemmick to have supper at his home, this odd character created by Dickens serves as an
example of the theme of Appearances vs. Reality.  For, unexpectedly, indeed, Pip is
brought to a world that seems completely out of character with the nondescript,
coldly-business-like clerk of Mr. Jaggers.  There, at his home, Wemmick exhibits warmth
and love toward his "Aged Parent," as well as a creative spirit which entertains his old
father.  The ritual of firing the canon, Wemmick tells Pip, helps to "sweep away the
Newgate cobwebs."  So, after Pip visits the home of Wemmick, he gains a new perception
of the man who becomes a valued friend.

Wemmick's little
museum of mementos taken from criminals also points to the humanness of this dual
character, and the differences between appearance and reality. When Wemmick conducts Pip
through the prison where the criminals greet the clerk as a friend, Pip realizes that,
although Wemmick seems wooden in the conduct of business in the office of Mr. Jaggers,
he--unlike Jaggers--does not dismiss the criminals as mere matters of business, after
all.   That he keeps things of these criminals points to Wemmick's having perceived them
as individuals.