The Ram's design was partly modeled on the Whitehead torpedo, and like it had cruciform control fins near the tail. The boat did not simply take on ballast until she sank like other contemporary submarines; she maintained a slightly positive buoyancy, and simply tilted her horizontal planes so that her forward motion forced her under.
The Ram was armed with a nine-inch pneumatic gun some eleven feet long, mounted along the boat's centerline and firing forward out of her bow. It operated like modern submarine torpedo tubes: a watertight bow cap was normally kept shut, allowing the six-foot-long projectiles to be loaded into the tube from the interior of the submarine. Then the inner door was shut and the outer opened by a remote mechanism. Finally, 400-psi air was used to shoot the projectile out of the tube. To reload, the outer door was again shut and the water in the tube was blown into the surrounding ballast tank by more compressed air.
During extensive trials, Holland made numerous dives and test-fired the gun using dummy projectiles. However, he was not making progress rapidly enough to suit his clients, and the Fenian Brotherhood stole the Ram in November 1883. They took the submarine to New Haven, Connecticut, but discovered that no one knew how to operate it. Holland refused to help. Unable to use or sell the boat, the Brotherhood had the Ram hauled into a shed on the Mill River. Her 15-hp engine was scavanged to operate a forge in a brass foundry.
In 1916, Fenian Ram was exhibited in Madison Square Garden to raise funds for victims of the Irish Uprising. Afterwards, she was moved to the New York State Marine School. In 1927, Edward Browne purchased her and moved her to Paterson, New Jersey, where she can still be seen.
Presumably as a tribute to this vessel, the submarine which features in Frank Herberts classic science-fiction novel of submarine warfare, 'The Dragon in the Sea', is named 'Fenian Ram'.