On board, there is every appliance known to modern naval engineering. The two condensers each have a cooling surface of 1,500 feet. A distilling plant for distilling salt water into fresh water is also supplied in the boat, as well as an air compressing and an electric lighting plant. Three boilers of the Mosher water-tube design give the needed power. They are powerfully constructed and will give a working pressure of 250 pounds to the square inch, with a heating surface of 8,325 square feet. Each boiler is to be supplied with a smoke-pipe standing about ten feet above the deck. The _O’Brien_ is low in the water and exceedingly hard to locate at night, even by the use of searchlights. She is a type of the advanced fighting machine, and her entire appearance denotes the fighter. Her armament is as follows: Three torpedo tubes, two forward, one aft, and three three-pound rapid-fire guns, located as are the torpedo tubes. When in commission she will carry a Whitehead torpedo in each tube, and additional ones on the racks near the tubes. The boat will carry sixty officers and men. * * * * * Speaking of the capture of the _Margaretta_, Capt. Edward O’Meagher Condon, a member of the American-Irish Historical Society, says in his excellent work:[59] “This was the _first naval fight_ of the Revolution, and Jeremiah O’Brien was the victorious commander. Two British cruisers, the _Diligence_ and _Tapnaguish_, were at once despatched to lay Machias in ashes, but they also were met and captured by O’Brien, his brothers and comrades. The young hero immediately sailed, with his prizes and prisoners, for Watertown, Mass., where the Provincial Congress was in session, and received the thanks of that body and a captain’s commission. But the British were not yet satisfied. They sent from Halifax a squadron, including a frigate, a twenty-gun corvette, a brig of sixteen guns, and several armed schooners, to crush the weak American fleet; but O’Brien, aided by Colonel Foster, was once more triumphant, and beat them off after a hard struggle. “They then sent a strong body of land forces against Machias, but after the second day’s march from Passamaquoddy the British troops returned to Halifax, despairing of effecting a passage through the woods, or, perhaps, hopeless of accomplishing their purpose when confronted by those who had already conquered their fellow-mercenaries three times at sea. We are told that Maurice O’Brien, old as he was, could hardly be restrained from joining his gallant sons in their daring enterprise against the British.