What happened at the ore-crushing mill?

At the ore-crushing mill, Edison was not satisfied with the work of the rock-crusher machine. He ordered the operator to give the machine another turn of speed. The operator replied that by doing so it would break. Edison asked the foreman about the cost of the machine. "Twenty-five thousand dollars.", came the reply. Knowing this Edison aske the operator again to give it another turn. As soon as the speed was increased, the machine broke and its pieces flew in all directions. Then Edison said to the foreman that he could put 40% more power than the machine could stand. Now he could build one just as good, and got more production out of that. With that he rolled up his coat, curled up on a table, and immediately fell asleep.