I meant to say this quite a while ago. Dave O, commented that the fifth string wasn't added till the 1840's or 50's. I am not an authority but a friend of mine, George (Butch) Wunderlich is and he sez that the banjo had five and sometimes six (double drone) strings as early as the end of the 18th century. All banjos were homemade. The maker built it the way he wanted it to be. Some have a drone 4th string and no fifth. He played it the way he wanted it to be played. Bents Fort was around for quite sometime. It went way past the rendezvous period, which ended roughly about 1840. Wunder Banjo Company sells an 1837 Boucher Tackhead which, except for it's 14" diameter head and 'treblecleft' fretless neck looks and plays like a "modern" banjo. I'll bet the banjo in the bookkeepers room is from around 1845 to 1860 (given the brackets) It surely seems like it is pre-civil war.