James Oliver and the chilled plow: the patent of 30 June 1857

1857–1873 · THE FOUNDATIONAL PATENT, AND WHAT "CHILLED" MEANT IN THE METAL

The patent: The document on which South Bend's inventive record stands is Letters Patent No. 17,694, "Improvement in Chilling Plowshares," granted 30 June 1857 — and its face names two inventors, not one: James Oliver and Harvey Little, the fellow molder who had bought into the South Bend foundry beside him in May 1855. The popular telling gives the patent to Oliver alone; the patent itself is joint, and it is printed here as joint. What the patent covered was a way of casting a plowshare so that the face which meets the soil came out of the mold with an extremely hard surface. The word "chilled" is a foundry term, and the metal explains it.

Cast the same iron against an iron chill — a cooled metal mold face — and the surface layer freezes so fast that its carbon has no time to separate as graphite; it hardens instead into white iron, a glassy, wear-resistant skin over a slower-cooled, tougher gray body. A chilled share would take and hold a mirror polish — it scoured — shedding the prairie soils that defeated ordinary cast iron, and it outwore them, while the soft core behind the skin kept the casting from snapping on a stone. Chilling as an idea was old: Robert L. Ardrey's American Agricultural Implements (1894), the period's own history of the trade, records that efforts to harden the wearing parts of cast plows ran back almost to the first cast plows and that "for more than half a century no one could master it." Ardrey's verdict, and the one this record adopts, is precise: "Credit for making the chilled plow a practical success is due to James Oliver." The process patent followed the share: in February 1869 Oliver took a further patent for his process — the company history calls it his annealing process — and the Dictionary of American Biography account gives the discovery at its heart: in 1869 Oliver learned that circulating hot water through the chills would keep castings from cooling too fast or unevenly, and then found how to bring the liquid metal into direct contact with the face of the chill, removing the soft spots and leaving the moldboard's surface smooth and flawless; by 1873 the basic improvements stood patented.

The engineering landmark account of the works compresses this into the 1857 story, crediting the hot-water regulation to the first patent's practice; the two accounts are printed as they stand, and the 1869 date for the controlled-cooling discovery is the biographical record's. The trail runs on in the patent files themselves: No. 217,898, "Improvement in Chilled Plow-Points," filed 26 June 1879 and granted 29 July 1879 to James Oliver of South Bend; and No. 557,999, a plow patent of 7 April 1896, James Oliver of South Bend, assignor to the South Bend Iron Works of the same place. The received count of his lifetime patents on plow designs is forty-five, carried as the attributed figure it is. The firm these patents built — the works, the sales, the 1929 merger — is the Businesses section's entry; what belongs here is that the foundational document of South Bend invention is a two-man patent for a way of freezing iron, and that the American Society of Mechanical Engineers has since landmarked the works that grew from it.

Sources:

1. United States Patent Office, Letters Patent No. 17,694, "Improvement in Chilling Plowshares," 30 June 1857, to James Oliver and Harvey Little — as cited from the Letters Patent in the Oliver Farm Equipment Company record.
2. Robert L. Ardrey, American Agricultural Implements (Chicago, 1894), "The Invention of the Chilled Plow" — the half-century of failed efforts and the "practical success" verdict.
3. Dictionary of American Biography account of James Oliver, via Encyclopedia.com — the 1869 discovery, hot water circulated through the chills, metal brought into direct contact with the chill face, the basic improvements patented by 1873.
4. Oliver Farm Equipment Company, the standard company history — the patent of 30 June 1857; the further process patent of February 1869; incorporation of the South Bend Iron Works 22 July 1868.
5. Invention & Technology (American Heritage / ASME landmark program), "The Oliver Chilled Cast-Iron Plow" — the hot-water chiller regulation as the works' landmark account gives it; 170,000 Oliver chilled plows in use by 1878.
6. U.S. Patents Nos. 217,898 (29 July 1879) and 557,999 (7 April 1896), the patents themselves, via the Patent Office images — Oliver of South Bend; the 1896 patent assigned to the South Bend Iron Works.
7. Wikipedia, "James Oliver (inventor)" — the forty-five lifetime patents, attributed; the 1868 patent for a large plow, citing Howard's county history.