Dr. Damian Nance, Distinguished Professor of Geological Sciences, was given a personal tour of a unique steam engine in San Francisco by the National Park Service this summer as part of a Baker Award project on the use of steam in 19th century mining technology.
Moored at Hyde Street Pier as part of the city’s Maritime National Historical Park, the Eurkea is the last American side-wheel paddle steamer to remain afloat. This 300-foot, double-ended ferry was launched as the Ukiah in 1890 to carry trains and their passengers across the San Francisco Bay and was rechristened the Eureka in 1923 following a massive overhaul.
Like hundreds of other side-wheelers that, in their day, provided cargo and passenger service on many of North America’s shallow bays, lakes and inland waterways, she was powered by a massive “walking beam” engine very similar to those used on mines throughout the 19th century.
Connecting rod end of the hollow-work beam on the Eurkea’s hurricane deck
As with all such engines, it was simple, compact, reasonably economical and easy to maintain. The engine, which is supported by a massive A-frame that rises the full height of the vessel, was powered by a single cylinder almost 5½ feet in diameter and more than 12 feet tall. It was capable of delivering 1500 horse power and could turn the paddlewheels at 24 revolutions a minute. To do so, the piston inside the cylinder and the connecting rod that turned the paddle crank were linked by a diamond-shaped, cast iron beam that nodded up and down above the hurricane deck as if it was walking. The Eureka was finally taken out of service in 1959.
Dr. Damian Nance
Nance’s description of this engine has since been published by the UK-based Trevithick Society, named for Richard Trevithick, a Cornish engineer who pioneered the use of high-pressure steam engines for transportation and mining applications.
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