Shortly after twelve Luna was surprised at seeing the superintendent enter the mill.
"Cut off the feed in the batteries."
The order was curt, and Luna, much bewildered, hastened to obey.
Firmstone followed him around back of the batteries, where automatic machines dropped the ore under the stamps. Firmstone waited until there began to come the sound of dropping stamps pounding on the naked dies, then he gave orders to hang up the stamps and shut down the mill. This was done. The rhythmic cadence of the falling stamps was broken into irregular blows as one by one the stamps were propped up above the revolving cams, till finally only the hum of pulleys and the click of belts were heard. These sounds also ceased as the engine slowed and finally stopped.
"Shall I lay off the men?" asked the foreman.
"No. Have them take out the screens."
This also was done, and then Firmstone, accompanied by Luna, went from battery to battery. They first scraped out the loose rock, and afterward, with a long steel spoon, took samples of the crushed ore from between the dies. The operation was a long one; but at length the last battery was sampled. Firmstone put the last sample in a sack with the others.
"Shall I carry the sack for you?" asked Luna.
"No. Start up the mill, and then come to the office." Firmstone turned, and, with the heavy sack on his shoulder, left the mill.
There were a hundred stamps in the mill. The stamps were divided into batteries of ten each. Each battery was driven separately by a belt from the main shaft. There was a man in attendance on every twenty stamps. Firmstone had taken samples from each battery, and each sample bore the number of the battery. He had taken especial care to call this to Luna's attention.