Dugan cut to the right and started down the slope. Halfway down he stopped. This was it!
A small-gauge track ran out from the rear of the factory and led up to a perfectly plain sort of quarry. Quite evidently, the air view would explain the track as an engineers' improvisation designed to bring stone down to the factory for further construction or road-building purposes. But this particular quarry had something possessed by no other quarry in the world.
It seemed inexhaustibly supplied with little trains. While Dugan watched, a tiny train steamed out of the quarry. He thought to himself and then wondered.
"Why do they use steam?"
His question was answered when he saw the smoke pattern in the air. It made the yard engine more believable. Who would electrify a mere yard line or expect a little steam train to continue underground? The steam locomotive had been obviously waiting in the quarry, behind some high wooden sheds. Its smoke made a big lazy pile in the air, where the engine had been waiting. The little train disappeared into the factory yard. Dugan thought, but was not sure, that he could see little human figures opening a gate in a fence for the little train to pass through.
Reaching into his shirt pocket, he took out a piece of steel, no thicker than a wire but beautifully machined. Into this he fitted two small lenses. Holding the gadget at the hooked end of the thin steel rod, he brought the factory yard into focus by careful manipulation of the forward lens. His miniature telescope worked.
Three soldiers guarded the gate to the factory. That was not in the least unusual. In the Soviet Union, paradise of the working class, all factory gates were guarded by soldiers. As he watched, they swung the gate open again.
The little engine scuttled out of the factory yard, across the open country, uphill to the quarry. With no train behind it, it made good speed — perhaps thirty-five or forty miles an hour. Dugan had trouble keeping his delicate telescope aligned upon it.
From within the quarry, once the engine disappeared, smoke began to pile up again in the mid-afternoon sky. But before the smoke had reached much volume — certainly before its pattern had attained the diffusion of the first wait of the engine — the little locomotive came popping out of the quarry again. With a new train.
"Popular sort of quarry," murmured Dugan to himself.