Despite the extreme secrecy of officials, indications were abundant in Washington tonight that the case of the American steamer Nebraskan, believed to have been torpedoed by a German submarine, was assuming great importance in the eyes of the United States Government. One evidence of this is found in the unusual pains that are being taken to determine by indisputable evidence whether the Nebraskan, which was damaged by an external explosion off Fastnet Rock, on May 25, was the victim of a torpedo or a mine. Despite the reports forwarded by Ambassador Page, the Administration is unwilling to base its conclusions in the Nebraskan case on the verbal evidence it already possesses. It has determined upon an independent expert, technical, and scientific examination of the "fragments of metal" that have been sent by Ambassador Page, in conjunction with the photographs that have been received. This investigation is being conducted by experts of the Navy Department, and will probably take about ten days. Robert Lansing, the Secretary of State ad interim, refused tonight to discuss the "fragments of metal" received from Ambassador Page in connection with the Nebraskan case further than to say that the reports received yesterday, with the photographs and accompanying exhibits, had been referred to the Navy Department. Josephus Daniels, Secretary of the Navy, said tonight that the report had been referred to experts of the Navy Department for a confidential report to be submitted to the State Department. Neither at the State Department nor from any official or officer of the Navy Department was it possible to obtain any further clue as to the character of the reports. It was learned that the reports accompanying the set of photographs and "fragments of metal" were not the original reports on the Nebraskan case, made by Lieutenants Towers and McBride, which were received by the State Department last week, but were in the nature of a second set of supplementary reports, based on actual examination of the battered bow of the Nebraskan and the technical examination of the interior of her forward compartment. This examination was made by Lieutenants Towers and McBride, while the Nebraskan was in a drydock at Liverpool. Photographs of the interior and exterior of the steamer's hull were taken by the naval experts. The "fragments" in question will be analyzed metallurgically for the purpose of ascertaining precisely what metal they contain. Generally speaking, torpedoes are made of a higher grade of metal, within and without, than that used in the construction of mines. The exterior metal of torpedoes consists of nickel steel and copper, and the interior mechanism includes the same kinds of metal and brass. The exterior shell of a mine is generally made of less expensive material, such as galvanized iron, but the interior mechanism and clock-work are of finer metal.