Sim Gage, sleepless so long, was very weary, but he kept about his work.
At intervals of half an hour he crunched down the gravel-faced slope of the bank which ran from the bench level to the foot of the dam.

Here he walked along the level of the great eddy, along the rocky shore, examining the face of the vast concrete wall itself, gazing also as he always did, with no special purpose, at the face of the wide and long apron where the waters foamed over, a few inches deep, white as milk, day and night.
Any attempt at the use of dynamite by any enemy naturally would be made on this lower side of the dam.

There were different places which might naturally be used by a criminal who had opportunity.

One of these, concealed from the chance glance of any officer, was back under the apron, behind the half-completed side columns of the spill gate, where a great buttress came out to flank the apron.

A charge exploded here would get at the very heart of the dam, for it would open the turbine wells and the spillway passage which had been provided for the controlled outlet.
Ragged heaps of native rock lay along the foot of the dam, flanking the edge of the great eddy eastward of the apron.