The German manufacturers evinced a keen interest in the project of a wireless plant in Nicaragua, laying special stress on the point that "permanent stations in this neighborhood" would be valuable "if the Panama Canal is fortified." From Sayville station the German plan projected powerful wireless plants in Mexico, at Para, Brazil; at Paramaribo, Dutch Guiana; at Cartagena, Colombia, and at Lima, Peru. A point in which Captain H. Retzmann, the German naval attaché in 1911, was at one time interested was whether signals could be sent to the German fleet in the English Channel from America without England's interference. German naval wireless experts supervised the construction, and although the stations were nominally civilian-manned, and purely commercial, in reality the operators were often men of unusual scientific intellect, whose talents were sadly underpaid if they received no more than operators' salaries. Gradually and quietly, Germany year by year spread her system of wireless communication over Central and South America, preparing her machinery for war. Over her staff of operators and mechanics she appointed an expert in the full confidence of the Embassy at Washington, and in close contact with Captain Boy-Ed. To the system of German-owned commercial plants in the United States he added amateur stations of more or less restricted radius, as auxiliary apparatus. When the war broke out, and scores of German merchantmen were confined to American ports by the omnipresence of the British fleet at sea, the wireless of the interned ships was added to the system. Thus in every port lay a source of information for the Embassy. The United States presently ordered the closing of all private wireless stations, and those amateurs who had been listening out of sheer curiosity to the air conversation cheerfully took down their antennae. Not so, however, a prominent woman in whose residence on Fifth Avenue lay concealed a powerful receiving apparatus. Nor did the interned ships obey the order: apparatus apparently removed was often rigged in the shelter of a funnel, and operated by current supplied from an apparently innocent source. And the secret service discovered stations also in the residences of wealthy Hoboken Germans, and in a German-American "mansion" in Hartford, Connecticut.