Iron Furnace

Iron Furnace (HM26WO)

Location: Franconia, NH 03580 Grafton County
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Country: United States of America
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N 44° 13.802', W 71° 45.287'

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Across the Gale River stands New Hampshire's sole surviving blast furnace. It is unusual, as well, in its octagonal shape and its remarkable condition.

A huge wooden shed protected the furnace and workers from the weather. The shed filled the area between the river and the upper terrace in the rear.

Iron ore was hauled in two-wheeled oxcarts from mines three miles to the southwest. The rusted wheelbarrow displayed nearby was used to feed charcoal, iron ore and limestone into the furnace from above.

Once started, the fire was kept roaring for four to six months. Air pumped from water-powered bellows fanned the coals. In later years, hot air was drawn off the top and piped down to the coals - the hot blast method.

When the iron ore melted, impurities floated to the top. This "slag" was drawn off the surface of the molten mass. Every 24 hours a clay plug near the bottom was removed, allowing liquid iron to flow into sand furrows and form iron bars called "sows" and "pigs."

Residents for miles around could see the reflected glow from the red-hot iron.

Some of the pig iron was remelted at a refining forge and converted to wrought iron. This malleable iron could be reheated and hammered into products by blacksmiths and foundrymen, or molded into iron bars.


pig iron was cast directly at the furnace into kettles and heating stoves, which were sold in the company stores here and in Bath, New Hampshire.

Iron pigs and products were shipped south on the Connecticut River from Bath.

The furnace and its site are privately owned. Trespassing is dangerous and forbidden.

HM NumberHM26WO
Placed ByIron Furnace Interpretive Center and Franconia Area Heritage Council
Marker ConditionNo reports yet
Date Added Monday, April 16th, 2018 at 1:01pm PDT -07:00
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Locationbig map
UTM (WGS84 Datum)19T E 279990 N 4901113
Decimal Degrees44.23003333, -71.75478333
Degrees and Decimal MinutesN 44° 13.802', W 71° 45.287'
Degrees, Minutes and Seconds44° 13' 48.12" N, 71° 45' 17.22" W
Driving DirectionsGoogle Maps
Area Code(s)603
Which side of the road?Marker is on the right when traveling South
Closest Postal AddressAt or near 149 NH-116, Franconia NH 03580, US
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