[en] Together, the two new Homestake detectors will be used to search for slow, massive magnetic monopoles; to study the zenith angle distribution of neutrino-induced muons; to search for neutrino bursts from the gravitational collapse of massive stars; to measure the multiplicity and transverse momentum distributions of cosmic ray muons; and to study the composition of the primary cosmic rays. Both instruments have been described in detail elsewhere; the authors discuss here the capabilities of the underground device as a detector of slow magnetic monopoles