Gardner guns suffered the fate of being invented after the Gatling and just before the machine gun. Thus, their role was already assumed by the pre-existing Gatling guns and they would be obsolete before the end of the 19th century.
Their role in the United States may have been taken by the Gatling gun, but Gardner guns did enjoy some international success. Several hundred 2 and 5 barrel variations were utilized by the UK’s Royal Navy and British Army, not to mention examples sold to the Netherlands and Denmark.
This example is one of the improvements of Gardner’s patents, after the manufacturing rights were sold to Pratt & Whitney of Hartford, CT. One of the company’s engineers, Edward G. Parkhurst, filed several patents for his water cooled barrels, tripod, and improvements to the feed mechanism. While approximately 250 of the improved Parkhurst Gardners were sold to Italy, only 21 were sold to the United States. This is #14 of those rare versions produced for U.S. War Department trials. Only 11 are known to survive today.