This Civil War-era 15-inch gun at Fort Monroe, Virginia weighed 50,000 pounds and carried a ball weighing 475 pounds from four to five miles. Jacob Williamson Hill of Jefferson, Iowa, demonstrated at Fort Monroe in 1870 a double-shotted projectile he invented the year before. Credit: Courtesy Library of Congress

A group of soldiers gathered at an artillery field on the grounds of Fort Monroe, Virginia, on Monday, Feb. 7, 1870. Under the command of Col. T.G. Baylor, they were conducting an experiment. The U.S. government had authorized the Army to carry out the testing of a new product designed by an Iowa man.

Jacob Williamson Hill of Jefferson, Iowa, had traveled to Fort Monroe to demonstrate his new and improved double-shotted projectile. He had taken out a patent for his invention in June 1869.


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Hill claimed his invention had a range of eight to ten miles and shot from the weapon could be discharged while in flight. The cone-shaped object, with a bore inside and a time fuse at the side, weighed 200 pounds. It held half a pound of powder. The projectile could be placed in a cannon and discharged.

According to the New York Times, the fuse was from five to 10 seconds; and at the end of that time, it ignited the powder and discharged 12-pound shot. The new projectile was designed to discharge the small shot when the cannon ball had reached its highest elevation. The large shot would be fired at an object, while the small one would be “very effective” firing at a line of troops.

On the day of the experiment, the first attempt failed. The plug in the end of the shot had not been screwed in correctly, causing the plug and the ball to fall out after traveling only about a mile. The second test was successful when the plugs were screwed in correctly.

Col. Baylor planned to provide a full report of the experience to the Chief of Ordnance at the fort. The current 15-inch guns that the army used threw shot only five miles. The newspaper reported that Hill was pleased with the outcome of the test, and he believed his new invention could fire a shot “almost any distance.”

Hill’s success at Fort Monroe may have inspired him to return to Iowa and develop more ideas. In 1870 he and Thomas Roberts from Panora were granted a patent for an improvement in rotary steam engines. They called their product a photo-uthographer. They wrote in their patent application that the “construction and novel arrangement” of the valves, piston blocks and steam ports lessened the “complexity” and enhanced the “efficiency” of the machine.

In 1872 he was granted a patent for a double furrow plough. And in 1873 Hill patented two more ideas. One was an improvement in weighing attachments for wagons. According to Hill’s application, his idea enabled the “load to be conveniently weighted without the necessity of driving to a platform scale.” And, Hill explained, the new invention would be “so constructed that the knife-edges will not be liable to wear while transporting the load.” He also was granted a patent for an improvement in combined brakes and propelling mechanisms for train cars.

“My invention is an improvement in the class of apparatus for propelling and braking railway trains, in which air is forced into suitable receivers when the train is checked,” Hill wrote in his patent application. In 1875 he received a patent for his design of a frame for portable steam.

Although Hill had plenty of creative ideas, it’s unclear if any of his inventions were developed and manufactured. To read detailed descriptions and see drawings of Hill’s inventions, visit



  • The Engineer, vol 34, Aug 1872, p xiv.
  • “A New Projectile,” New York Times, Feb. 12, 1870.
  • “A New Projectile By An Iowa Inventor,” Quad-City Times, Feb. 12, 1870.
  • Official Gazette of the US Patent Office, vol 7, 1875, p 304.
  • Scientific American, July 10, 1869, p 29.

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