. . . . . . . . . . . . . . . . . "Abstract. We present a deep, new 1200-\u03BCm survey of the ELAISN2 and Lockman Hole fields using the Max-Planck Millimeter Bolometer array (MAMBO). The areas surveyed are 160 arcmin2 in ELAISN2 and 197 arcmin2 in the Lockman Hole, covering the entire Submillimetre Common User Bolometer Array (SCUBA) 8-mJy survey. In total, 27 (44) sources have been detected at a significance \u22654.0\u03C3 (\u22653.5\u03C3). The primary goals of the survey were to investigate the reliability of (sub)millimetre galaxy (SMG) samples, to analyse SMGs using flux ratios sensitive to redshift at z> 3, and to search for \u2018SCUBA drop-outs\u2019, i.e. galaxies at z\u226B 3. We present the 1200-\u03BCm number counts and find tentative evidence of a fall at bright flux levels. Employing parametric models for the evolution of the local 60-\u03BCm IRAS luminosity function, we are able to account simultaneously for the 1200- and 850-\u03BCm counts, suggesting that the MAMBO and SCUBA sources trace the same underlying population of high-redshift, dust-enshrouded galaxies. From a nearest-neighbour clustering analysis, we find tentative evidence that the most significant MAMBO sources come in pairs, typically separated by \u223C23 arcsec. Our MAMBO observations unambiguously confirm around half of the SCUBA sources. In a robust subsample of 13 SMGs detected by both MAMBO and SCUBA at a significance \u22653.5\u03C3, only one has no radio counterpart. Furthermore, the distribution of 850/1200-\u03BCm flux density ratios for this subsample is consistent with the spectroscopic redshift distribution of radio-detected SMGs. Finally, we have searched for evidence of a high-redshift tail of SMGs amongst the 18 MAMBO sources that are not detected by SCUBA. Although we cannot rule out that some of them are SCUBA drop-outs at z\u226B 3, their overall 850-to-1200 \u03BCm flux distribution is statistically indistinguishable from that of the 13 SMGS which were robustly identified by both MAMBO and SCUBA." . . "A 1200-\u03BCm MAMBO survey of ELAISN2 and the Lockman Hole - I. Maps, sources and number counts" . . . . . . . . . .