When Navy divers and NOAA National Marine Sanctuary marine archaeologists recovered the USS Monitor steam engine from the Atlantic in 2001, the pioneering Civil War propulsion unit was covered in a thick layer of marine concretion. Sand, mud and corrosion combined with minerals in the deep Cape Hatteras, N.C., waters to cloak every feature of Swedish-American inventor John Ericsson's ingenious machine, and they continued to envelop the 30-ton artifact after nine years of desalination treatment.
So just this past month, conservators at The Mariners' Museum and its USS Monitor Center drained the 35,000-gallon solution in which the massive engine was submerged for nine years and began removing the 2- to 3-inch-thick layer of concretion with hammers, chisels and other hand tools.
Working slowly and carefully to avoiding harming the engine's original surface, they stripped off more than 2 tons of encrustation in their first week of work alone, gradually revealing the details of a naval milestone that had not been seen since the historic Union ironclad sank in a December 1862 storm.
Get an insider's look at this work and the Monitor's engine out of the water for the first time in nearly a decade.
Information from Jeff Johnston, program specialist with the Monitor National Marine Sanctuary: The Monitor's steam engine was rated at around 400 horsepower and capable of pushing the ship through the water at 6 - 6 1/2 knots.
This unique side lever steam engine has been undergoing active conservation since its arrival at The Mariners' Museum in July 2001. The process is a slow and lengthy one designed to remove chlorides (salt) that have penetrated the ferrous metals down to their core. A thick layer of marine concretion covered the components that were exposed above the sea bed for 139 years prior to recovery. The conservation process loosens this concretion to where it can be carefully removed form the components revealing the original components where they survive. The iron underneath of thsi concretion is now very weak on the surface and in some areas is no longer really classified as metal. What remains is a graphitzed surface that is soft and brittle and it has to be stabilized through the conservation processes.
Many of the smaller iron components of the links and levers associated with the engines running or operating gear have completely deteriorated away inside of the concretion and when removed we are only left with a shell casting of what was once there. Sadly the materials the machinery was originally made from has actually contributed to its deterioration in seawater. The brass and bronze components are in incredible condition, but their material encourages iron components to act almost as a sacrificial anode corroding away in preference to the brass and bronze.. So wherever there is a bearing, oilier, or valve, the iron in that area is usually in far worse condition that areas that are iron on iron components.
Once the engine has completed its conservation process, it will be placed on display inside of the USS Monitor Center at The Mariners' Museum. As incredible as a working USS Monitor steam engine would be on exhibit, the exhibit will be purely static as the condition of the materials of the machinery and its associated components are far to fragile to ever to have them operational again.
We currently have an artifact inventory of 1,344 components, sub components and associated artifacts that have been recovered from the Monitor. These include a wide variety of materials including glass, ceramics, wood, leather, food stuffs, paper, and leather. The larger components recovered include the Monitor's 9-foot cast iron propeller, the 32 ton steam engine and associated components, and of course the world's first rotating gun turret that was recovered intact in August 2002 with the two XI-inch Dahlgrens, their carriages and hundreds of artifacts from within the turret.
Learn more about Monitor National Marine Sanctuary: monitor.noaa.gov/
28 дек 2010
