midnight
At last , just before midnight , the incandescence did not come back to the globes , and the men gathered in groups to discuss the matter and express heated opinions of the efficiency of the men in charge of the lighting plant . The workmen moved about here and there in the shadows and clambered like ants over the great bulk of the dam . No one looked to see that the men assembled in the workings all belonged there . At midnight four men who did not belong there entered the excavation which leads from the bottom of the lower lock to the sea-level channel into Limon Bay , which is a child of the Caribbean Sea . These four men moved about as if accustomed to the situation , only now and then they halted and whispered together . Other men , workmen , were doing that , however , and so these four passed on up to the foot of the spillway without attracting attention . Here they separated , one to the west , one to the east , where the locks are , and one to a position half way between the spillway and the west side of the locks .