The officers gather for what they call the rock drill, a last session of planning.

A rock drill was supposed to be used but, when used it broke.

From his perch on the fourth floor, Graham threw the rock drill.

Johnny's shift had left the rock drills in place, still connected to the compressed air system, ready for use.

After the rock drill, platoons meet between the tents.

They carried with them an extra spool of superfiber and a rock drill.

With the production of rock drills a change was made again to the business of metal machining.

Right next to the riverbank, men are already at work with rock drills, placing dynamite charges.

The rock drill began to bite into the loosely-packed topping of gravel.

Here a temporary power station was established for rock drills, lighting, compressors, etc.