On location at Sandon BC in front of the Prospectors Pic and Sandon Visitor's Center (Old Sandon City Hall) on Main street.

Porter #104 is believed to be one of only several compressed air locomotives left in North America. These locomotives typically operated in mines to haul rail cars in and out of the underground workings. Working off of compressed air, they didn't emit any exhaust fumes harmful to miners. They were also a low risk in creating sparks (I.e.. In coal mines where it was essential to avoid igniting the coal dust). The locomotive would have had its big 1" thick riveted receiver tank filled up with air to 800 psi (pounds per square inch) The main reservoir pressure was dropped to 250psi working pressure through a regulator. This model was driven by a double expansion set of cylinders (the air got used twice, in two stages of expansion), a much more efficient machine than the single expansion units. Other compressed air locomotives can be seen at the BC mining museum, Fort Steele, BC, Jaffray BC, Canmore Alberta and Heritage park in Calgary.

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Sandon is one of many mining ghost towns in British Columbia, Canada. It is also the birthplace of hockey legend Cecil "Tiny" Thompson.

Sandon is located in the Selkirk Mountains, about ten kilometers east of the town of New Denver. After the discovery of vast amounts of galena ore here by Eli Carpenter and Jack Seaton in 1891, prospectors flocked from around North America to stake their claims. For a short time, Sandon had more than 5,000 residents and a booming economy. Two different railways raced to reach the town first; the Kaslo & Slocan Railway, connecting Sandon with nearby Kaslo, on Kootenay lake, and the Nakusp & Slocan Railway, from New Denver and Nakusp. Well into the 1900s, the hills around Sandon were actively mined by mines such as the Silversmith, the Slocan Star and The Payne. Smaller communities, such as Cody and Three Forks appeared on the map, continuing to provide opportunity to the miners. Like the other silver towns of the era, Sandon faded with the silver prices, and in 1951, a massive flood of Carpenter Creek swept away most of the town. Today, all that is left of the once-great Sandon are a few buildings and a handful of residents. Both railways that served the town have been dismantled and turned into hiking trails, leaving only traces of a rich mining history.

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Charles B. Hodges invented a two-stage engine employing a reheater between the two piston stages to warm the partially expanded compressed air. This air was passed through a heat exchanger, which was warmed by the ambient air, drawn through it by using the exhaust air in an ejector. Simiiar ejectors (blown with steam, not air) were commonly used to generate the vacuum used by locomotive braking systems. This ingenious development eliminated the need for bouillottes and little coke fires, and introduced no new moving parts. Air was the only fluid employed. A substantial gain in range was attained; up to 60% appears to have been possible. The H K Porter Company of Pittsburgh bought the rights to Hodge's US patents and sold hundreds of locomotives so equipped to coal-mines in the eastern USA, in the period 1896-1930. They were used extensively in gassy mines where explosions were an ever-present danger. No doubt the cold exhaust air was once more welcome to supplement the mine ventilation.

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