19th Century 14-String Zheng
From the Royal Museum of Art and History in Brussels, Belgium we have this Carmentis record of a 14-stringed zither made sometime before 1900, coming in at 141.2cm or ~55 inches in length.
I don't know enough to date the instrument, but its style dates from before the modern changes and seems to be closer to the Tang Dynasty style, though it's proportionally closer to the Japanese koto. An earlier black and white photo shows this particular instrument before its strings broke, at which time it had 14 visible bridges.
Source: Royal Museum of Art and History, Brussels, Belgium