for launching torpedoes at the Schiavon shipyard in Fiume. The ship was equipped with a launching barrel, which was Whitehead's invention. More than 50 launch trials were performed in front of the factory, in Fiume harbour bay. Gemses commander, Frigate Lieutenant Count Georg Anton von Hoyos, later married Whitehead's daughter Alice.

By 1870, Whitehead had managed to increase the torpedo's speed to 7 kn and it could hit a target 700 yd away. The torpedo was driven by a small reciprocating engine