four o'clock
exclaimed Ames , starting off rapidly toward the trail . `` I 've got pull that 'll surprise you . '' Jim swore a little under his breath and began again on his interrupted calculations . When the four o'clock whistle blew and the shifts changed , some one sat down silently near Jim . Jim worked on for a few moments , finishing his problem . Then he looked up . Suma-theek was sitting on a rock , smoking and watching Jim .