The Army and Navy Journal thinks the problem of a torpedo boat capable of firing rapidly and with certainty, has at length reached a satisfactory solution. It says:

"A boat has been completed which is proved by experiment to be faultless in machinery and arrangement. On the 2d of December, Secretary Robeson, Vice-Admiral Porter, and Commodore Case, Chief of the Bureau of Ordnance, went to the Navy Yard at Washington, to witness the experiment with this new engine of destruction. After examining the workings of the machinery, and the manner of firing, one of the destructives was put in the frame and the party proceeded to the shore to witness the result. A torpedo of only thirty-six pounds was first run out with rapidity and fired; but the result showed that this small amount of powder, even, would have been sufficient to destroy any ship, by lifting her out of the water and breaking her back, even if her bottom was not knocked out altogether. Mud and water were thrown up together, and the concussion was felt far up in the Navy Yard, the ground being shaken by the shock of the powder against the bed of the river. The concussion felt on board the torpedo-boat was not more than that caused by a wave striking a vessel at sea.

"Several torpedoes were fired from the vessel, the explosion of which the party witnessed on board, as they desired to ascertain for themselves the effect of the shock. The result seemed satisfactory, as no change whatever is contemplated in the machinery, which is very simple, and 'works to a charm.' The torpedo vessel is the Nina, a very strong iron boat of three hundred and fifty tuns burden, capable of crossing the ocean, and having a speed of seventeen knots an hour. She is not impervious to heavy shot, but can be made so, and is capable of resisting any ordinary projectile that could be brought to bear on her from the decks of a ship of war. Her decks will be made torpedo and shot-proof, and several arrangements will be applied, now that it is known that the torpedo system is a success. Such a vessel as the Nina, attacking an enemy's squadron on our coast some dark night, or entering an enemy's port, could destroy half the vessels in the harbor, and easily escape as few vessels could overtake her. Such a vessel could, for instance, enter the harbor of Havana, and destroy every vessel of war in the port, under cover of darkness. A squadron supplied with such boats to be used to attack, after the fight began, and the ships were enveloped in smoke, would have a most decided advantage against an enemy not thus armed for torpedo warfare. It is reported that our torpedo navy will consist of twenty vessels, none of which will have a less speed than twelve knots, and the fastest of them will go seventeen knots."