Scientific, nautical, geological, geodetic, radiotelegraphic, navigation, photographic, optical, weighing, surveying, measuring, signaling and calibrating apparatus and instruments and parts thereof for collecting high resolution magnetic data; gradiometer system comprised of five caesium vapour magnetometers in row configuration transverse gradient indicators; Sonars; Sonar apparatus, namely, sonar equipment and parts thereof; Underwater sonar navigational and surveying apparatus for use in ...