USS PRINCETON shot gauge 1843

By John L. Morris

Pictured is a shot gauge for round shot for a 12-inch naval gun, dated 1843, made at the Washington Navy Yard, DC.  The marking line “12 * 11 * 80” means it is for a 12 inch gun, and allowing for windage, the maximum diameter of the shot is 11.80 inches, the inside diameter of the steel ring.  Other markings include date and place of manufacture “U * S * W * N * Y” (United States Washington Navy Yard.). Each shot intended for loading into the 12 inch gun was rolled along a trough a short distance with the ring gauge encircling it to ensure no shot were over-diameter in any plane.  This was done as part of the inspection/acceptance process for the shot when delivered from the contractor.   USS PRINCETON was armed with two experimental 12-inch wrought iron guns, one of which, dubbed “Peacemaker,” exploded during a demonstration for many embarked dignitaries, killing several and wounding many.  This was almost certainly the shot gauge used to inspect the 11.8 inch diameter shot loaded aboard PRINCETON before her fateful cruise on the Potomac river.  No 12-inch guns were owned by the US Navy during that period of history, save the four 12-inch guns were built for this project, driven by notable US Navy CAPT. Robert F. Stockton.  One was cast iron, and exploded during testing ashore.  Of the three wrought-iron guns built, one exploded aboard PRINCETON as mentioned, and the other two are now displayed in the Washington Navy Yard and at the US Naval Academy respectively (the latter pictured here:  https://www.usni.org/magazines/proceedings/2013/june/lest-we-forget-princeton-and-peacemaker). Artifact pictured:  Private collection of Virginia antiques dealer.  The most comprehensive article known to the author, encompassing the entire episode is here: https://web.mit.edu/~sgtist/Public/princeton.pdf