Northern Junction

Twenty-seven minutes after halting for water, Belfast No. 1 pulled out of West Elmont Depot, accelerating back to cruising speed.

This time, Ernest took a seat in the rear inspection coach alongside Samuel and King Edward, while Hollen remained up on the locomotive footplate, claiming he wanted to monitor the draft dampers personally.

Ernest unfolded the longitudinal profile map across the oak table. "We are approaching the first sustained grade on the line: the approach to the High Saddle. A ruling gradient of one point two percent over six continuous kilometers."

Arthur looked up from his ledger. "Is that the hill you spent three weeks surveying around to avoid building a tunnel?"

"It is," Ernest confirmed. "Now we discover whether our tractive calculations hold under sustained operational load."

The gradient began almost imperceptibly, but the locomotive felt the change in resistance immediately.

CHUFF! ... CHUFF! ... CHUFF! ... CHUFF!