I paused the discussion of 6-pdr field guns after presenting the Model 1841. Although that model is the most successful and widely produced American 6-pdr, it was not the final word in the class. Indeed, several experimental and limited production batches of 6-pdrs, outside of the Model 1841 series production, appeared in the two decades before the Civil War. I mentioned two such batches in passing when relating the experiments leading up to the Model 1841. On the chart below, the bottom three lines note three experimental batches procured after the Model 1841. For this post, let me focus on the rather interesting background of the Treadwell guns.
Daniel Treadwell hailed from Ipswitch, Massachusetts. Born in 1791, by the late 1830s Daniel Treadwell was successful inventor and established businessman (and held the Rumford professorship at Harvard). Treadwell’s successful inventions included a power printing press and a hemp spinning machine. The later gave him an introduction to many in the Department of the Navy. (A lengthy examination of Treadwell’s professional career appeared in Volume XI of the Memoir of the American Academy of Arts and Sciences, published in 1888).
For reasons not entirely clear (likely as with most inventors, he was just curious), in 1840, Treadwell took up the study of cannon design with an aim to resolve the problems confronting the designs of the time. In his published study “A Short Account of an Improved Cannon”, published in 1845 (sections cited in the above mentioned Memoir), Treadwell considered the issue of cannon endurance in light of the metal tenacity. To Treadwell, spring steel appeared the most desirable metal, followed by wrought iron. He further elaborated upon the ‘fibers’ of wrought iron, concluding the arrangement of the metal influenced the ability to withstand pressure. Treadwell felt the best construction used wrought iron in a spiral around the axis of the bore. This, he felt, put the resistance to pressure on a diagonal direction as opposed to a longitudinal direction.
And don’t be concerned if this is not perfectly clear. It’s physics, and worse yet is based upon the understanding of metalurgy in the 19th century. Sort of a dense subject explained through a faded lens of understanding! So I tend to put less emphasis on the validity or “proof” of Treadwell’s theory and more on the simple fact he was advancing a new idea about cannon construction at that point in time.
Putting his thoughts into practice, Treadwell produced a 4-pdr gun built upon connected wrought iron cylinders or rings. The gun “withstood the actions of enormous charges of powder and was only burst by using very superior powder, and shot without windage.” Using that as a basis, Treadwell produced additional experimental guns and refined his construction. By June 1841, he was able to file a patent caveat. Diagrams from the full patent, filed in 1845, provide an illustration of the inventor’s refined technique.
At first glance, the spiral approach reminds me of that employed by John Griffin in his patent leading to the famous 3-inch Ordnance Rifle. But Treadwell’s earlier design, although using a mandrel like Griffin’s approach, layered the metal differently.
This “new” technique established, in March 1842 Treadwell proceeded to the War Department and advanced his ideas – what we might call today an “unsolicited proposal.” Presenting the concept to Secretary of War John Spencer, Treadwell impressed otherwise skeptical Ordnance Chief Lieutenant-Colonel George Talcott. Apparently the use of a steel mandrel to form the inner portion of the gun had some influence on the Army officer. At the end of the visit, Talcott recommended a test batch.
Treadwell proceeded back to Massachusetts to setup a foundry and shop to produce these guns. There are some discrepancies with regard to the number produced. Some sources, citing receipts, state the number was seven (which is what I’ve gone with in the chart above). Others indicate a production total of nine guns (with one duplicate registry number). Treadwell indicates delivering six for tests in 1843 and mentions additional test samples later. Nine would seem a reasonable number. Descriptions indicate the guns followed the Model 1841 external form, but with a welded band mounting the trunnions.
The first six guns arrived at Fort Monroe in late 1843 where Captain Benjamin Huger was in charge of the testing. The first tested, recorded as registry number 4, fired 1,501 shots. Showing little wear, the Army then proceeded to test number 4 and number 3 with progressively larger powder charges and number of shot. The tests concluded with firing six pounds of powder and seven solid shot. The guns apparently passed the endurance test, but Huger noted some erosion at the welds of the gun.
Although these tests proved Treadwell’s predictions about the gun’s durability, the Army was not ready to open up the check book. Further Huger expressed concern about flaws in the guns noted before firing. In part to address the later, the Army sent Huger to Treadwell’s foundry in order to observe the production technique (which is when I think the additional three guns appeared). Impressed, Huger offered some improvements to the process but further suggested Treadwell consider guns of larger caliber.
In April 1844, Talcott recommended production of cannon using Treadwell’s patent in 6- and 12-pdr field gun and 12- and 24-pdr howitzer calibers. However, the “cutting edge” factor played into the procurement. Treadwell’s guns cost more than the standard bronze pieces in those respective classes. The Army didn’t have the funds to procure large numbers of Treadwell guns. And bear in mind the testing concluded just before the USS Princeton explosion in 1844, in which a wrought iron gun failed with disastrous results.
At the same time Treadwell courted Army contracts, he was also wooing the Navy. These efforts eventually lead to a set of 32-pdrs for testing, two of which survive today at the Washington Navy Yard.
But the story of that Navy gun is for another post (as well as the example produced for France, much to the alarm of the Navy!). But I post the photo here as the only example of Treadwell’s work accessible for most students of artillery. Apparently one of Treadwell’s 6-pdrs did survive all the tests and years in storage. In 2007 pictures of a gun very much fitting the description appeared on one internet forum. The gun is in private hands currently.
Although failing to secure large orders, the Treadwell gun represents an evolution in construction. In some regards Treadwell foreshadowed some of the rifled field pieces that served in the Civil War.