Mayne Reid,
The Free Lances: A Romance of the Mexican Valley
“ In daylight it would have been difficult enough, yawning chasms to be crossed barransas—with cliffs to be climbed, in comparison with which the escarpments of the Pedregal were but as garden walls.In a groping way, hand helping hand, all were at length got up and over, as the tolling of distant church bells, down in the valley below, proclaimed the hour of midnight. Just then Rivas, once more making a stop, plucked a leaf from one of the grass plants growing by, and placing it between his lips gave out a peculiar sound, half screech, half whistle—a signal as the others supposed ”
