Good subject; I thumbed through Ripley's "Artillery and Ammunition of the Civil War". The below link shows a 10" Model 1841 Siege Mortar, now at Fort Point, San Francisco, Ca.

http://svsm.org/gallery/us_mortar

According to Ripley's book this gun is shown in a photograph at Fort Barrancas at some point. It was apparently moved to a fort that never engaged in ANY Civil War activity.

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David Upton