Muenter's insane attack on Mr. Morgan, because he had failed to "use his influence to prevent the exportation of arms and ammunition," followed the wrecking of the United States Senate reception room in the Capitol at Washington on July 2 by the explosion of an infernal machine set by Muenter. On July 6 a trunk owned by Muenter containing twenty pounds of explosives was found in New York. During his stay in jail Muenter wrote to his wife that two ships were to sink at sea on July 7, if his calculations went right, naming the Philadelphia and the Saxonia. The ships were duly warned by wireless, but no bombs were found aboard them, nor were any confederates of Muenter discovered. On July 7 the steamship Minnehaha reported by wireless a "fire caused by explosion" under control. Incendiary bombs had been discovered aboard four freight steamships sailing from New York for Havre in April and May. On July 12 Secretary of the Navy Daniels, acting on advices received from The New Orleans Picayune, directed the naval radio station at Arlington, Virginia, to flash a warning to all ships at sea to be on the lookout for bombs supposed to have been placed on board certain vessels, and warning particularly the steamers Howth Head and Baron Napier that information had come to the Navy Department that explosive bombs might have been placed on those two vessels. All ships were requested to try to communicate with the Howth Head and the Baron Napier. On July 11 a written threat to assassinate J.P. Morgan, Sir Cecil Spring-Rice, the British Ambassador, and destroy by bombs British ships clearing from American ports, thus carrying out some of the plans of Erich Muenter, was reported in a letter signed "Pearce," who styled himself a partner and intimate associate of Muenter. This letter was received by The New Orleans Times-Picayune.