Here the lone member of class S1a, No. 6000, reposes briefly in the yards of the Cincinnati Union Terminal in this photo from my brother David's collection. It was taken in September 1954, but the photographer is unknown. The Class S Niagaras were intended for fast passenger service and were designed to accept 79-inch drivers for this purpose. However the first example, No. 6000, was delivered with 75-inch drivers because of a wartime restriction on building new passenger locomotives. The 25 engines of the S1b class came shortly after the end of World War II and were built with the higher drivers. By the time this photo was taken No. 6000 had also been so equipped.

The S1s had a boiler pressure of 275 pounds per square inch and 25½x32-inch cylinders, and developed a tractive effort of 61,570 pounds. Their trailing truck supported a firebox with 101 square feet of grate area. This, combined with an evaporative heating surface of 4,819 square feet, produced a maximum drawbar horsepower of 5070 at 62.5 miles per hour, the equivalent at that time of four diesel units. The total weight of locomotive and tender was 891,000 pounds.