The extremely weak S(4) and S(6) electric quadrupole transitions of the 3-0 band of nitrogen have been detected by very high sensitivity CW-Cavity Ring Down spectroscopy near 6950 cm(-1). A noise equivalent absorption on the order of alpha(min) similar to 6 x 10(-13) cm(-1) was achieved by averaging several thousand 0.5 cm(-1) wide spectra recorded successively over several days. The studied N-14(2) lines are among the weakest ever measured in the laboratory (intensity on the order of 1.5 x 10(-31) cm/molecule). The positions determined with a 0.002 cm(-1) uncertainty and the line intensities are compared with theoretical values included in the HITRAN2012 database. (C) 2013 Elsevier B.V. All rights reserved.