This article from Frank Leslie's Illustrated Newspaper in 1856 depicts a "stuffer's ballot-box." The false sides and bottom allowed "stuffers" to conceal extra ballots for their candidate. By covertly sliding the panels, dishonest partisans could mix the forged ballots in with the legally cast votes without ever disturbing the box's lock. The possibility of this type of electoral fraud led reformers to design ballot boxes immune to stuffing. One model included a crank through which the ballot passed and imprinted with a seal to prove its authenticity.
"Stuffer's Ballot Box," Frank Leslie's Illustrated Newspaper, (July 19, 1856): 92.