As Pennsylvania petroleum production skyrocketed following the Civil War, Densmore oil tank cars – designed and fabricated by two inventive brothers – first successfully transported oil by rail from booming oilfields to refineries.

densmore oil tank car

Amos and James Densmore designed their first twin tanked railroad cars in 1865. They improved bulk transportation of oil. Photo courtesy the Drake Well Museum.

densmore oil tank car

Although prone to leaks and top heavy, Densmore tank cars provided a vital service – but only briefly. A better railroad car replaced them.

Railroad oil tank cars became the latest of a growing number of oilfield innovations when two brothers received a U.S. patent on April 10, 1866.

James and Amos Densmore of Meadville, Pennsylvania, were granted the patent for their “Improved Car for Transporting Petroleum,” which they developed one year earlier in the booming oil region of Northwestern Pennsylvania.

Using an Atlantic & Great Western Railroad flatcar, the brothers secured two tanks in order to ship oil in bulk. Patent no. 53,794 describes and illustrates the railroad car’s design.

The nature of our invention consists in combining two large, light tanks of iron or wood or other material with the platform of a common railway flat freight-car, making them practically part of the car, so as they carry the desired substance in bulk instead of in barrels, casks, or other vessels or packages, as is now universally done on railway cars.

The brothers described the use of special bolts at the top and bottom of the tanks to act as a braces and “to prevent any shock or jar to the tank from the swaying of the car while in motion.” 

An historical marker on U.S. 8 south of Titusville memorializes the Densmore brothers’ contribution to petroleum transportation technology.

The first functional railway oil tank car was invented and constructed in 1865 by James and Amos Densmore at nearby Miller Farm along Oil Creek. It consisted of two wooden tanks placed on a flat railway car; each tank held 40-45 barrels of crude oil.

densmore oil tank car

Riveted cylindrical iron tank cars replaced Densmore brothers’ wooden vat cars. Discarded Densmore tanks can be seen in the foreground. Photo courtesy Drake Well Museum.

densmore oil tank car

The Densmore brothers invent one of the first typewriters.

A successful test shipment was sent in September 1865 to New York City. By 1866, hundreds of tank cars were in use. The Densmore Tank Car revolutionized the bulk transportation of crude oil to market.

According to an ExplorePAhistory.com article, the benefit of such cars to the oil industry was immense – it cost $170 less to ship eighty barrels of oil from Titusville to New York in a tank car than in individual barrels. But the Densmore cars had flaws.

They were unstable, top heavy, prone to leaks, and limited in capacity by the eight-foot width of the flatcar.

Within a year, oil haulers shifted from the Densmore vertical vats to larger, horizontal riveted iron cylindrical tanks, which also demonstrated greater structural integrity during derailments or collisions.

The same basic design for transporting petroleum is still used today as railroads have put  dozens of other products – from corn syrup to chemicals – in the versatile tank car.

From Oil to Typewiters

Although the Densmore brothers left the oil region by 1867 – their inventiveness was far from over.

In 1875, Amos Densmore assisted Christopher L. Sholes to rearrange the “type writing machine” keyboard – so that commonly used letters no longer collided and got stuck. The “QWERTY” arrangement vastly improved Shole’s original 1868 invention.

Following his brother’s work with Sholes, inventor of the first practical typewriter, James Densmore’s oilfield financial success helped the brothers establish the Densmore Typewriter Company, which produced its first model in 1891.

The ExplorePAhistory.com article concludes:

“Biographies of the Densmores – and even their personal papers now residing at the Milwaukee Public Museum – all refer to their work on typewriters, but make no mention of their pioneering work in railroad tank car design.”

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