magnetic anomalies
... that an instrument used to measure magnetic anomalies was originally developed to detect submarines during World War II?
... that an instrument used to measure <b id="mwDd8"><a href="./Magnetic_anomaly" id="mwDeA" rel="mw:WikiLink" title="Magnetic anomaly">magnetic anomalies</a></b> was originally developed to detect <a href="./Submarine" id="mwDeE" rel="mw:WikiLink" title="Submarine">submarines</a> during <a href="./World_War_II" id="mwDeI" rel="mw:WikiLink" title="World War II">World War II</a>?