Looking thru some microfilm I had made many years ago from records in the National Archives, I noticed these unusual entries regarding two small bronze mortars used by the US navy in the "Sound Survey Expedition" back sometime in the mid-19th C. This particular portion of an old ledger book shown miscellaneous guns that were at the New York Navy Yard at the time the entries were made (unknown but certainly late 19th C.) The only information is that there were two of the mortars, bronze, with two inch bores, which weighed 54 pounds each. These specs are very much like those of a two-inch thunder mug, so I wonder it that's what they were? I see from the second page that they were in the US Centenniel Exposition in 1876, so maybe someone can find a picture of them in one of the books about that exposition. I may ask the folks at the Navy museum and the Naval Historical Center also, they may even have one of the things in storage, you never know. I've gotten the impression that the bulk of their artifacts are in storage.
Hopefully you will be able to make out the images which are obviously in negative format, photographed off the screen of a microfilm reader in a library.
