Cornwall Plaque Cornwall Furnace Boiler Closeup Charging House
Cornwall Plaque Cornwall Furnace Boiler Closeup Charging House
Diagram of Air Blow System Steam Engine Blower Wheel Air Tubs
Diagram of Air Blow System Steam Engine Furnace Blower Wheel Air Tubs
Front of Furnace Tapping Hearth Side Tuyere Rear Tuyere
Front of Furnace Tapping Hearth Side Tuyere Rear Tuyere


Cornwall Furnace is completely restored complex, with the blast furnace, furnace building, and charging house still standing. Since much of the original structure was made from brick rather than wood, the overall structures remain as they were over a century ago. The site is run by the Pennsylvania Historical and Museum Commisson. There is a small fee to tour the site, but the donation is well worth the cost - particularly as they depend heavily on donations (rather than state monies) to fund this educational opportunity.

The existing furnace is actually the third furnace to be constructed at Cornwall. The first was a temporary bloomery furnace built approximately 1/2 mile from the current site. The second furnace was also a cold blast furnace with one tuyere. It had a stack of 31 feet and a 9 foot bosh. The blast was achieved through bellows, driven by a water powered wheel. The remains of the aquaduct that powered this wheel can be seen along the outer wall of the furnace grounds. This initial production furnace was built in 1742 and ended operations in 1856.

During the period of 1856-57, the current furnace was built, utilizing much of the second structure. The newest furnace had three tuyere's, and the blast was changed from water powered to steam engine. Additionally, the bellows were replaced by air tubs. It is 31 feet 8 inches tall with a 7 foot bosh.

These air tubs are quite interesting in their construction. The outer portion is basically a barrel of wooden staves held together with an iron hoop. The head of the barrel was made out of heavy, thick wood and fastened to be as air tight as possible. The interior of the barrel was polished smooth to reduced friction, and kept uniform in size. On the side of this outer cask were two valves. The valves were made from wood with a leather facing. On the inlet valve, a pivoting counterweighted lever closed the valve when the suction action was stopped. At the outlet valve, a spring closed the device when the compressed air had been delivered to the reservoir. The interior of the tub consisted of another barrel, built just slightly smaller than the inside diameter of the outer cask. This primitive piston was attached to a wooden connecting rod, which then completed a series of mechanical linkages back to the the steam drive flywheel. The action of each tub forced air into a reservoir located between them. The reservoir consisted of a wooden box and a movable (accordion) top. Due to a large weight placed on this movable top, the reservoir air was forced down a 1 foot diameter pipe into the furnace. Pressure in the pipe was approximately 1 psi, but was sufficient to deliver air to the furnace.

First Visited: 3Q 2002


Start of Operation: 1742 (1856 current structure)

Blowout: 1856 (1883 current structure)

Daily Tonnage: 2,000 tons/year, or 7.5 tons/day based upon a 9 month production schedule

Built By: Peter Grubb, Samuel Grubb, Joseph Taylor

Stack: 31 feet, 8 inches w/7 foot bosh

Blast: Cold

Type: Charcoal

Cornwall Furnace is one of the oldest iron producing sites in the United States. Peter Grubb was a mason who built a temporary bloomery furnace about 1/2 mile from Cornwall to determine the viability of iron production. It must be remembered that in this period, Lancaster County in Pennsylvania was largely unexplored territory. Having achieved successful results on his trials, Peter acquired nearly 1000 acres of land in 1737 and 1738. Along with his brother (Samuel Grubb) and a local blacksmith (Joseph Taylor), he built present day Cornwall Furnace between September 1739 and 1742. In 1745, he established the Cornwall Company, which consisted of the Cornwall Furnace and the Hopewell Forges, along with the land holdings for iron ore and charcoal production. This proved to be significant, as he suddenly passed away in 1754. Since he did not have a will, the Commonwealth divided the properties between his two sons according to existing law - 2/3 of the estate was given to the oldest son (Curtis Grubb) and 1/3 to the youngest (Peter Grubb). However, since the properties were held by the Cornwall Company until 1765.

Initially, Curtis Grubb did not take a significant interest in the operations of the Cornwall Company, leaving daily management of the operations to the younger son, Peter. The primary reason for this arrangement was due to the fact that Curtis was unhappily married - since he could not obtain a divorce allowing for remarriage, he legally separated from his wife by living in France for several years. He left in 1756, and since there was no contact for six years, he was declared legally dead, and his first wife remarried. Then Curtis returned, claimed his inheritance, and could now remarry in the future. During his stint in France, Peter possessed power of attorney to run the combined operations. Upon his return in 1760, Curtis took over operations at the furnace, while Peter (who had more experience with iron) ran the forges. While they both wanted to assure the ongoing success of the operations, their personal relationship was not close. These tensions were increased in 1774 when Peter's wife died during the birth of their second child. Peter never remarried, although he did father an illegitimate daughter with his housekeeper (Dec 1774). After his wife's death, Peter evidenced both a temper and drink, neither of which helped him in future years.

The period surrounding the American Revolution created even more tensions between the two brothers. While both were Patriots, Curtis associated himself with the radical political camp, while Peter favored the moderate wing. While the entire history of events during this period is extensive, the basic result was that Curtis became quite well known (and respected by members of Congress), while Peter struggled through several military setbacks, and was overall relegated to "second fiddle" in terms of external viewpoint regarding the Cornwall Company.

This unhappy situation continued after the war, and was exacerbated by the third marriage of Curtis. His son (by second marriage), was Peter Grubb Jr., and this individual was particularly anxious about his financial future in light of his father's upcoming nuptials. In particular, Peter Grubb Jr. was concerned that his inheritance would be diluted by any children resulting from this third union. In response, Curtis and Peter decided to give Peter Jr. his inheritance prior to the marriage. In order to accomplish this, it became necessary to specifically define the Grubb assets, rather than merely split the furnace and forge operations. As part of the legal arrangements, Peter's minor sons (Alan and Henry) would inherit 2/3 interest in the forges, but only 1/3 interest in the furnace and the ore site.

Peter became increasingly concerned that his brother could cut off access to the raw ore and smelting process, effectively blocking supply to the forges. To mitigate this risk, he began building Mt. Hope Furnace in 1784. However, Curtis believed that Peter was attempting to ruin him financially. Since forged iron sold for 16 times the price of pig iron, the Cornwall Furnace operations would not enable him (or Peter Jr.) to enjoy a profitable enterprise. The two opposing viewpoints led to a bitter feud between the two brothers. The dispute continued until May 1785, when a combination of factors (including drink), resulted in Peter committing suicide. In the meantime, Peter Jr, being increasingly worried about the financial outcome of the dispute, sold his inheritance to Robert Coleman in early 1785.

In 1786, Curtis and Peter's lawyer (representing Peter's minor children) established an agreement between Curtis, Peter's sons, and the new partner - Robert Coleman. When Curtis died in 1789, the remain Grubb heirs did not have an interest in actually running the iron operations, so they sold out to Robert in 1802, except for a 1/6 share of the ore banks. At their peak, the Coleman family owned 9,669 acres of land and several furnaces/forges. The Coleman family operated the furnace and the forges until 1883.

Owing to the quality of the site and the availability of information regarding the Grubb and Coleman families, there is a wealth of information about the operations of the Cornwall Iron Works.

Cornwall Iron Ore Banks. These ore banks were literally the foundation of the Cornwall site. The site is commonly referred to as the "Big Hill", the "Middle Hill" and the "Grassy Hill." The iron was quarried rather than mined, and was shipped not only to Cornwall Furnace, but to other local furnaces as well. According to the Lebanon Historical Society, the ore removed from this site between 1742 and 1907 was somewhere in the range of 15.6 to 20 million tons.

Labor. The Cornwall Iron Works utilized a wide variety of nationalities and included freemen, indentured servants, and slaves. Indentured servants were primarily immigrants from Germany or England who could not afford passage, and indentured themselves to an individual as repayment for the cost of passage. They tended to escape at the earliest opportunity, so Cornwall used very few of these workers through 1784, and did not appear to use any after this date. Slaves were used up to 1780, when the Commenwealth abolished slavery. Additionally, during the Revolutionary War, the furnace used Hession prisoners of war as woodcutters.

Pay. Pay for the workers at Cornwall Iron Works was considered quite good for the day. Examples of wages paid:

However, the wages must be placed into context - most workers were compensated with room and board. In 1865, workers paid $15/month for board and $20/year for housing. Deducting these expenses, a filler's actual bring home was about $10/month. Most workers also purchased their food, clothing, and frills at the company store. Depending on the era, the company sometimes sold goods at a profit, other times at cost. Due to these factors, the overall cash layout to the workers was typically very small. Despite these factors, most workers stayed at the furnace. The company records show that in many cases, families were employed for generations. For example, the Shay family members were employed as founders for nearly six decades. Additionally, the paternalistic nature of the furnace operations ensured that workers were "taken care of" during economic dropoffs. It was not uncommon for the Grubbs (or Colemans) to employ workers in the building of roads during periods of inactivity due to lack of orders. In many cases, the owners reduced or eliminated housing/board costs during these periods to retain their workers.

The Cornwall Iron Works were a very profitable operation. In 1786, Robert Coleman paid Peter Grubb 8,500 British pounds for a 1/6 interest in the furnace, placing the value of the business at 51,000 pounds. By 1832, the estate settlement of Robert Coleman valued the holdings at $280,000. Net profits through the 1840's ran between $12,000 and $21,000 per year.

Much of the information about the Cornwall Furnace noted above was drawn from the following two sources:


Take PA 322 East from Harrisburg to Cornwall. Follow the posted signs - the site is a primary tourist attraction in the city and is well marked.

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