schoonerbumm,
Bull's eye!! Right on every count. And right about the mine too. How did the Cutty Sark turn out? When I was a kid, all models turned out great!
The Cairo class or city class river gunboats. Designed by Samuel Pook and known as Pook's Turtles. The ships were built on speculation by James Eads, who in 1874, built a bridge across the Mississippi River at St Louis that was at the time the worlds longest arch bridge. He was the first engineer to use hydraulic caissons to sink the bridge piers and as a by-product, discovered what came to be known as caissons disease, or the bends. The bridge is still in use.
You can see the St Louis arch in the background of this picture taken from the East St Louis side of the Mississippi river. When Ead's drove one of the piers down through the mud, his men had to dig through a sunken riverboat to find bedrock.
schoonerbumm, the next question is yours.