Forest Iron Blues

Hi Sanford Smith here with Penn State Extension.

This video is going to be covering forest history.

And today I'm standing next to an old iron furnace in central Pennsylvania.

And we're going to be learning about how the iron industry impacted forests.

I'm going to be using this site, the Monroe Furnace Site, and comparing it to the Hopewell Furnace in southeastern Pennsylvania.

So you have a better idea and can envision how forests were utilized to make iron.

The first place I want to show you today at Monroe Furnace is the site of the charcoal House.

It was a barn like house that was located about 15ft uphill from the iron furnace.

It was constructed to protect the hardwood charcoal that was used as fuel to melt the iron ore.

All that is left today, of this house are some scattered stones and buried bands of charcoal that was left in the charcoal house around 1865.

As the state widened the nearby highway.

In later years, they exposed some of this old charcoal.

The building is thought to have had stone walls with wooden rafters and wood shingles on its roof.

The charcoal House at Hopewell Furnace helps us envision and understand this type of building.

It is a single room stone structure that had a cooling shed on its side.

This shed was open sided and incoming charcoal was dumped onto the ground here.

When it was brought back in wagons from the forest.

Here it was checked for heat and if needed, cooled off and then moved into the charcoal house.

Both furnaces burned between 5 and 7000 cords of wood turned into charcoal each year.

This means that in the mid 1800s, to run all of central and southern Pennsylvania's 150 furnaces, the iron industry was clearcutting and calling about 1.5 million acres of forest annually.

That's a lot of wood, especially when you consider that the iron industry began in the late 1700s and went all the way to the beginning of the 20th century, the early 1900s.

The next place to view at Monroe Furnace is the site of the former bridge.

The bridge was an elevated walkway about 20ft in length, that went from the charcoal house to the top of the furnace.

It was used to transport the ingredients needed to make iron to the top of the furnace, and it's very likely that the bridge had a roof over it as well.

The bridge ended in a small structure on the top of the furnace called the bridge house.

The furnace was loaded or charged from inside the bridge house every day, day and night, first with charcoal, then with iron ore, then with limestone, which was used to remove the impurities from the ore.

These were all poured down through a chute called the tunnel head.

It was hard, hot and dirty work, charging an iron furnace.

The layout of Hopewell Furnace was very similar to Monroe's, except that the charcoal house wasn't much higher than the top of the furnace.

So the bridge here was more like a ramp.

The bridge house at the top of the furnace is just as it was, and several furnace charging carts once used to haul the charcoal.

The ore in the limestone are still on site.

Iron furnaces needed lots of air for burning charcoal, and to get air they needed water.

There was a water course or race here at Monroe Furnace that today is a little hard to recognize.

It's a small stream channel that was hand dug into the side of the hill that slowly moved water down from a pond about a half a mile away.

When the water reached the furnace, it ran into a wooden sluice, which took it into the side of the building that surrounded the furnace.

Once inside, it spilled onto and turned a very large water wheel.

The water wheel at Hopewell Furnace almost matches what we suspect was at Monroe.

The water wheel here was used to move two long shafts up and down, and this power was mechanically transferred to pistons that ran air blowing tubs.

These functions somewhat like large bicycle pumps, as they pumped air into a metal duct that connected into the bottom of the furnace.

This air helped to increase the temperature and the rate of burn in the furnace, so that it could reach 3000°F for efficiently smelting the ore.

The key location of any iron furnace was the casting arch.

This was where everything came together.

Fortunately, it is still intact at Monroe Furnace Ruins, though it was once enclosed in the cast house.

This was where the founder, the most skilled iron worker, oversaw all aspects of production, and especially tapping.

Tapping was when the molten iron was released by the founder from the base of a furnace.

It occurred two times per day, and the iron was either cast into bars or poured into sand mold flasks to make useful objects such as pots, pans, stoves, or cannons.

As you may expect at the Hopewell Furnace National Historic Site, the cast house and its arch are still intact and filled with many interesting tools and exhibits about charcoal, iron making.

It's a wonderful place to visit, and many of the original buildings and equipment that were once part of the furnace community are present and well maintained.

Lastly, there were impacts of the iron industry on forests, while iron furnaces owned huge tracts of land that they repeatedly clearcut.

In 25 year cycles.

This type of extensive cutting proved to be unsustainable as the industry expanded.

Some furnaces simply ran out of available wood on their land.

Forests lost soil fertility to erosion and wildfires.

Many areas of older trees were converted to young stands of sun loving tree species that were different than the previous charcoal making species.

And wildlife habitat was degraded, contributing to population declines and species shifts over large areas.

It's true that forests are resilient and renewable, but charcoal making resulted in some very negative legacy impacts which are still observable today.

Well, I hope you enjoyed these tours of Hopewell and Monroe Furnace, and now have a better understanding about how forests help to make iron and what a big impact this industry had on our forests throughout the northeast.

Thank you very much for listening.