The more usual name for the item is "Line Throwing Gun." Aka "Lyle Gun" named after the US designer of this type, David Lyle.
We've got a few in the collection since that's one of the first types of cannons we owned. Some of our early ones include:
-Manby mortar, cast iron, on original square iron base
-Hall 2.5 inch, bronze, on orig. wood/steel mount
-Hall 3.5 inch, bronze, with steel portion of mount
-U.S. "Lyle" type as shown above, Watervliet arsenal 1929
-Unknown cast iron gun with 2.5-inch bore, shaped like U.S. Lyle gun but larger exterior dimensions, probably ca. 1900*
-Costen steel gun with center trunnions
*if anyone thinks they know who made that one, please let me know, Paul Barnett was not familiar with it.