A trip to Europe, looking at foundries: The 1840 Ordnance Commission

Last week’s post about foreign 6-pdr field guns was a “resource” post, if not an outright setup posting.  Sort of a background discussion leading me up to some points about European cannons and influences upon American designs.  What I am leading up to is this cannon:

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This cannon marks the battery position for 8th Indiana Battery at Chickamauga (Viniard Field).  At first glance this looks like any old bronze 6-pdr.

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Liège…as in Belgium.

And there’s this bit of service history proudly displayed on the muzzle:

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This weapon’s history takes us back to the end of the 1830s when Joel Roberts Poinsett was Secretary of War.  Aside from introducing the poinsetta to the United States, Poinsett had a very active life as a public servant – Congressman (1821-25), Minister to Mexico (1825-29), and Secretary of War (1837-41).  And, standing apart from many of his fellow South Carolinians, was a strong unionist during the Nullification Crisis.  So Poinsett is an interesting fellow to say the least.

As Secretary of War, Poinsett was a reformer.  In brief, Poinsett proposed many changes to the system of regular and militia forces, aiming for more formality and standardization.  At the low end of reforms, Poinsett pressed for new manuals and better weapons.  But at the high end, Poinsett wanted concentrated Army garrisons, summer training maneuvers that incorporated the militias, and expanded weapon manufacturing facilities.  Some of these reforms got through Congress.  But those on the high end didn’t.

Looking specifically at artillery, the Poinsett years are marked by a series of model numbers for field artillery, easily traced with the history of the 6-pdr guns – Models 1838 and 1840 along with the Model 1841.  And in-between were many experimental types.  Much debate among ordnance officers, and with Poinsett himself, in those days as the Army struggled to find a suitable field piece (arguably, much of that because the Army wanted the “perfect” field piece).

This came to a head in March 5, 1840, when Poinsett wrote the Ordnance Board that he was “…not satisfied that the corps, collectively or individually, posses that practical knowledge which the importance of the subject, both to the country and the reputation of the corps, would seem to require.” Very damning assessment from the boss.  But Poinsett didn’t just call out a problem, he also brought a remedy.  On March 16, Poinsett sent a letter instructing the Ordnance Department to detail a commission of three officers, and one civilian, on a trip to Europe with the mission of gaining the said practical knowledge.  In his letter of instruction, Poinsett wrote:

In the first place, it will be the duty of the board to acquire, as far as may be practicable, all practical knowledge which actual observation may afford upon the following objects, viz:

  1. The process of moulding and casting iron and brass cannon.

  2. The nature of the iron ores and pig metals used, and the treatment of the metal before and during the casting.

  3. The kinds of copper and tin used, and the proportions composing the metal for guns.

  4. The description of furnaces, and the kinds of fuel used in them.

  5. The modes and regulations for the inspection and proof of iron and brass cannon.

These broad objectives meant the board needed to gather information about the process of cannon production from the mines up to the foundry and out to the field.  Continuing with the instructions, Poinsett also authorized the purchase of samples:

The board will likewise obtain, by purchase, iron and brass guns, according to patterns which they are authorized to establish, in numbers sufficient to form a few field batteries; and they will give as much of their personal attention to their fabrication as time will allow, taking specimens of the metals in proof bars, of suitable dimensions for the necessary experiments and tests.

It is that paragraph which authorized the purchase of the cannon pictured above.

The commission consisted of Major Rufus Lathrop Baker, Captain Alfred Mordecai, Captain Benjamin Huger, and former ordnance officer, William Wade (who maintained partnership in a foundry in Pittsburgh, which later became Fort Pitt Foundry).   After spending the summer and much of the fall in Europe, the board returned to provide a very lengthy, detailed report. No doubt, that detail served to impress upon Poinsett that the desired “practical knowledge” was indeed obtained and retained.

In the report, the board provided a full accounting of all purchases.  Specific to the 6-pdr types, there were:

  • Two 6-pdr American pattern field guns, of iron, from Gospel Oak works, Birmingham, England.
  • Four 6-pdr American pattern field guns, of iron, from foundries in Sweden.
  • Two 6-pdr American pattern field guns, of iron, from the Liège, Belgium foundry.
  • Four 6-pdr American pattern field guns, of bronze, from the Liège, Belgium foundry.

Of that last quartet, two were cast in clay.  The other two cast in sand molds.  As you can see, the secretary’s intent was carried out.  There were sufficient 6-pdrs to outfit three batteries.  And that’s just the light field guns, not counting the heavier 12-pdr field guns and howitzers also purchased at the same time.

These weapons were, as alluded to in the letter, not intended for service use.  Rather these were earmarked for testing.  Most of that, tests to determine the weapon’s breaking point.  Destructive testing.

In a report from March 1844, on the extreme proof of a 6-pdr iron cannon cast at South Boston Foundry (Cyrus Alger & Company),  William Wade mentioned the foreign iron guns.  He compared the performance of the 1844 South Boston gun to tests of at least some of the foreign 6-pdr iron guns between 1841 and 1842 at Fort Monroe:

Of the six guns tried, three were cast in at different furnaces in Sweden, one in England, one in Belgium, and one in the United States.  Two of these burst with the charge of 3 pounds of powder and two balls; one at the 38th, and the other at the 39th fire of the series.  Three of them burst with the charge of 3 pounds and 3 balls; two at the 47th and one at the 49th fire.  The other, one of the Swedish guns, endured once the charge of 6 pounds and 7 balls, and burst at the second, being the 52d fire of the series.  The force of the charge last mentioned, under which the Swedish gun failed at the second fire, is computed to be less than that endured by all the [1844 guns]; the weakest of which, endured that force a greater number of times than the Swedish gun.

So that accounts for five of the eight foreign purchased iron guns.  It also indicates American cannon manufacture progressed smartly in just three short years. Some of that due to Wade’s “practical knowledge” and further experiments.

But what of the bronze guns?  I have not found any details of the tests.  But one of the other Belgian guns survives and is also on display at Chickamauga on the north end of the battlefield, at Douglas’ Texas Battery:

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This one is marked as registry number 4.  That at the 8th Indiana Battery is registry number 1.  In my next post, I’ll provide a walk around of these two historic pieces.  For closing now, let us consider these as “artifacts” which speak to a time of reform within the US Army.  These were “samples” used to derive “practical knowledge” in the art of cannon production.

(Citations from Report of Select Committee, to Inquire Into the Propriety of Establishing a National Foundry for the Purpose of Fabricating Ordnance, Report No. 229, 27th Congress, 3rd Session, US House of Representatives, 1843, pages 242-6; “Report of the Manufacture and Proof of 6 Pdr Iron Cannon Cast at the South Boston Foundry: 1844,” by William Wade, from Reports of Experiments of the Strength and Other Properties of Metals for Cannon, US Ordnance Department, Philadelphia: Henry Carey Baird, 1856, pages 16-17.)

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Origins of the Rodman – Early Experiments in the Rodman Method, Part 2

In part one, I discussed two 8-inch Columbiads cast in 1849 and used to test the Rodman method of casting large guns.  The conclusion of that experiment indicated a slight improvement to the gun, but not great enough to prove the hollow-core, water-cooled method was greatly superior.  Gunfounder William Wade suggested more tests with better quality metal.

Lieutenant Thomas J. Rodman, working closely with Wade, waited until 1851 for the next full-scale tests.  Fort Pitt Foundry cast another pair of 8-inch Columbiads – one solid and one hollow-core – on July 30, 1851.   Then on August 21 of that year, Fort Pitt cast a similar pair of 10-inch Columbiads.  Wade selected what was considered high quality iron from Greenwood Furnace of New York.

Rodman revised the cooling technique after the first experiment.  For this 8-inch hollow-core columbiad, the gunmakers left the insert in the gun bore for the first twenty-five hours of cooling.  The insert (just as with the earlier experiment) consisted of a tube, closed at the bottom.  Inside that tube, a smaller diameter tube, open at the bottom, allowed water to flow down into the bore.  The water then ran off from the top of the casting mold into a trough.  All the while, a fire burned under the casting mold in the open pit to slow the overall cooling of the gun.

Diagram of Rodman Casting Arrangements

After that initial cooling phase, the foundrymen removed the core and let water flow directly into the now hardened gun bore.  Excess water continued to run out from the top of the casting mold into the trough.  This continued for forty hours.   About halfway through that period, the gunmakers extinguished the fire in the pit, allowing the gun to cool completely in the last twenty hours.  Wade indicated that for the 8-inch Columbiad 10,000 cubic feet (300 tons) of water circulated through the gun during the entire sixty-five hours of cooling.

As seen on the fracture diagrams supplied by Wade, the guns conformed to the Model 1844 pattern.

Fracture diagram of 8-inch solid cast Columbiad No. 3

Casting of the 10-inch hollow core Columbiad differed in both measures and technique.  Foundrymen left the core insert in the bore of the 10-inch Columbiad for ninety-four hours.  At that time extraction failed, as the bore had contracted around the core.  With the interior tube removed, water continued to flow at a reduced rate into the 10-inch Columbiad for an additional forty-eight hours.  Although Wade does not state such, presumably the core insert was drilled or wedged out after the final cooling cycle.

There was one other critical difference in the casting of the 10-inch hollow-core Columbiad.  Because the casting mold (both solid and hollow castings) for the 10-inch Columbiad were not large enough to allow what Wade considered sufficient clay, the foundrymen placed both 10-inch Columbiads in a pit filled with “green sand” to ensure the hot metal did not melt the casket of the casting mold.  This, as we shall see, changed the cooling rates and performance of the gun.

Fracture diagram of 10-inch solid cast Columbiad No. 5

With the guns cooled, all four went to the range.  The 8-inch Columbiads went through test firings between August 28 and October 2 of that year.  The 10-inch Columbiads followed in October 7 to October 18.  Just as with the 1849 tests, all four guns fired from a test mounting.  Gunners supplied proofing charges for the first two fires.  The 8-inchers fired a 12 pound charge for the first shot then a 15 pound charge for the second, after which the guns fired a 10 pound standard service charge.  Likewise the 10-inch Columbiads first fired a 20 pound charge, followed by a 24 pound, then settling on the 18 pound service charge.  The 8-inch Columbiads shots alternated between a 63 ½ pound solid shot or a 49 pound shell.  The 10-inch Columbiads fired 124 pound solid shot and 91 pound shells.

Wade reported a mixed bag of results:

  • 8-inch Columbiad, No. 3, cast solid – burst after 73 fires
  • 8-inch Columbiad, No. 4, cast hollow – survived 1500 fires
  • 10-inch Columbiad, No. 5, cast solid – burst after 20 fires
  • 10-inch Columbiad, No. 6, cast hollow – burst after 249 fires

The description of the bursting of 10-inch No.5 speaks to the power of black powder.  Wade wrote, “…the upper part, weighing 4400 pounds, was thrown upward, and fell in the rear, about 80 feet distant.  In its flight, it broke a limb of a tree, on a hill side, sixty feet above the level of the gun when fired.”

While the 8-inch No. 4 proved an excellent argument in favor of Rodman’s method, the 10-inch No. 6 dampened that success.  Upon examination of the fragments, Wade noted several cavities and fissures in the metal even describing some sections as “sponge-like”.  Wade attributed these flaws to the use of sand for exterior cooling, estimating that seven-tenths of the heat dissipated through the exterior as opposed to the water in the interior.  Most of these fissures appeared on the front part of the gun.  One large fissure was noted on the fracture diagram, along the chase of the Columbiad.

Fracture diagram of 10-inch hollow core Columbiad No.6

However, Wade insisted the fissures did not cause the gun’s failure.  As he noted, the crack in the gun started over the chamber and proceeded forward along the barrel, crossing over the fissure.  Instead, Wade attributed the failure of the gun to the brittle nature of the metal overall, a property caused by the rate of cooling of the gun.

Examination of the gun metal at the conclusion of these tests indicated, just as with the 1849 tests, no significant difference in the tensile strength of the metal of the different guns.  After assuring the paired castings took place under identical circumstances with the same batch of raw metal, Wade proclaimed, “The great difference of endurance must therefore be ascribed, to the different methods by which the castings were cooled; and to them alone.” The method, as Wade and Rodman would explain in detail, allowed the gun to contract upon itself while cooling, thus changing the way the metal reacted to the stress of firing.

In his report Wade made the conclusion that casting large caliber guns required even more fastidious selection of metal for gunmaking, calling for softer and weaker iron that underwent a managed cooling process.  He further added,

The method devised by Lieutenant Rodman, for accelerating the cooling of the interior of the guns, by passing a stream of water through them, and for retarding, at the same time, the cooling of the exterior, by surrounding it with heated air, appears to lead in the right direction, even if it does not fully accomplish the purpose designed.

Wade recommended further tests, with 32-pdr caliber guns in addition to the large caliber columbiads, with the aim to refine the process further.  (To my knowledge, the 32-pdr experiments were never conducted.)  CORRECTION: I overlooked the mention of tests in 1852.  Details in the next post in this series.

Rodman’s technique required even more refinement and some concurrent experiments with metal composition before it would bear fruit at the end of the 1850s.  As with many successful weapon systems throughout military history, the Rodman gun was not so much “revolutionary” but rather “evolutionary.”

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References:

William Wade.  “Report on the Manufacture and the Extreme Proof of two 8 inch Columbiads and of two 10 inch Columbiads….” dated January 24, 1852.  Reports of experiments on the strength and other properties of metals for Cannon. Philadelphia: Henry Carey Baird, 1856,  Pages 181-204.

Olmstead, Edwin, Wayne E. Stark, and Spencer C. Tucker. The Big Guns: Civil War Siege, Seacoast and Naval Cannon. Alexandria Bay, NY: Museum Restoration Service, 1997, Appendicies C115 and C142, pages 237 and 253.

Origins of the Rodman – Early Experiments in the Rodman Method, Part 1

I’ve mentioned the Rodman technique for manufacture of heavy cannons on a number of occasions.  That process, simplified to a thumbnail, involved casting the gun in a hollow mold then cooling the metal from the inside out using a flow of water through a pipe in what would become the bore.  This allowed the interior metal to cool faster than the exterior.  In the cooling process, the gun compressed itself around the bore, providing the highest strength at the very part of the gun most needed.

Before we get too far though, let’s set the record straight.  Thomas J. Rodman did not invent hollow casting.  In fact, many of the earliest cast cannon were hollow core.  Not until the early 1700s did solid casting become the dominant means of production.  By the American Revolution, gunmakers cast weapons as a complete block, then cut out the bore after cooling.   But as gun calibers and powder charges grew larger, some began to ponder other ways to construct stronger guns.

In addition to testing different metal composition, construction techniques, and exterior forms (recall the experimental 6-pdrs), gunmakers revisited hollow casting in the late 1840s.  In 1849, Fort Pitt Foundry received an order to produce two 8-inch Columbiads for tests – one cast solid and the other cast “… according to the plan invented by Lieutenant Rodman, on a hollow core, through which a stream of water passed while the metal was cooling.”

Civilian ordnance inspector (and later foundry owner), William Wade reported these two guns shared the same metal composition, furnace, and other production details – save of course the casting technique.  The hollow Columbiad cooled for forty hours with water flowing through an insert.  Then the gunmakers removed the insert and cooled for another twenty hours with water flowing through the empty, recently cooled, bore.  All told the process used 6000 cubic feet of water.

Both guns went to a test range (presumably near Pittsburgh).  The Columbiads first fired reduced charges for initial tests of both the guns and the support apparatus.  Satisfied the arrangements were set, the crews then started firing full service charges – 10 pounds of powder, one sabot, and either a 63 ½ pound solid shot or a 49 pound shell. The guns fired alternatively through the proof firings. The ordnance inspectors made meticulous observations after each firing, particularly noting the level of vent erosion.

The solid cast Columbiad burst on the eighty-fifth shot (firing a shell).  Firing the hollow core Columbiad continued until it burst on the 251st shot.  Both guns split through the reinforce to the breech, but at different planes of fracture.  Wade recorded the general shape of the breech fragment in his report:

Fort Pitt used the Model 1844 Pattern then in production, which featured base ring along with first and second reinforces.    Wade reported that metal samples were removed from sections of these fragments for further testing.  From those samples, observers concluded the hollow core Columbiad exhibited slightly higher density and tensile strength.  However this slight increase in strength was, in the words of Wade, “… not sufficient to account satisfactorily for the strongly marked difference in the endurance of the two guns.”

Concluding his report, Wade submitted:

No other cause for this unequaled endurance can be perceived, but that of the different methods by which the castings were cooled. The precautions taken, to ensure an equality of the material composing the two guns, and to preserve an exact uniformity in their respective proofs, were such, that the different endurance cannot be ascribed to inequities in either of these respects.  Neither of the guns, however, endured a sufficient number of fires to be satisfactory.

While promising, clearly the hollow-core, water-cooled process required more refinement.  Wade recommended another round of experiments, this time with 10-inch Columbiads cast from higher quality metal.  I’ll look at those tests next.

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References:

William Wade.  “Report on the Manufacture and the Extreme Proof of two 8 inch Columbiads….” dated October 26, 1849.  Reports of experiments on the strength and other properties of metals for Cannon. Philadelphia: Henry Carey Baird, 1856,  Page 169.

Olmstead, Edwin, Wayne E. Stark, and Spencer C. Tucker. The Big Guns: Civil War Siege, Seacoast and Naval Cannon. Alexandria Bay, NY: Museum Restoration Service, 1997, Appendix C115, page 237.

Casting Tests: More Experimental 6-pdr Guns

Turning again to the chart of experimental 6-pdrs of the 1830s and 1840s:

The last two lines on the chart are two batches of trials and experimental iron guns from Cyrus Alger in Boston, Massachusetts.  While technically not “field guns” these two batches offer a glimpse of the Ordnance Department’s attempts to determine the best way to handle cast iron.

Perhaps the best place to start the story is in 1840 again, with the commission Secretary Poinsett sent to Europe.  According to the Congressional Report, Major Rufus Lathrop Baker, Captain Alfred Mordecai, Captain Benjamin Huger, and former officer and foundryman William Wade visited Europe in the summer and fall of 1840.  The commission observed foundries in Sweden, England, France, Russia, Prussia, and Belgium.  The men paid special attention to the iron handling in the European foundries.

The commission purchased several guns while visiting Europe.  In reference to the discussion of 6-pdrs, the officers acquired two iron 6-pdrs from Gospel Oak Works near Birmingham, England; four iron 6-pdrs from three different Swedish foundries; two iron and four bronze 6-pdrs from the royal foundry in Liege, Belgium.  All the foreign guns followed the “American pattern” according to the report.  The Army tested these guns, along with two West Point iron guns.  The Swedish guns performed a little better than others during the tests.  But as noted in an earlier post, the Ordnance officers concluded the European iron was not significantly better than American iron.

While bronze was the solution for field guns, the Americans needed iron for the siege and seacoast guns.  Toward that end, William Wade continued experiments focused on the properties of cast iron.  In February 1844, the Army issued a contract to Cyrus Alger to produce four 6-pdrs, each cast under different handling processes:

  • No. 1 – cast directly after the iron was melted.
  • No. 2 – cast after the iron was in fusion for one hour.
  • No. 3 – cast after the iron was in fusion for two hours.
  • No. 4 – cast after the iron was in fusion for three hours.

The pattern used, reproduced here from a diagram in the report, was noteworthy for its lack of adornments, rings, and muzzle swell.

Wade's 6-pdr Trials Guns

Wade reported the guns had the same weight and length as contemporary bronze types, but of course to a different form.  What appears as a “band” on the breech is really a thick reinforce and part of the casting.   As cast, the guns suffered many imperfections.  So Wade rejected those and had another set cast.

For the tests, Wade noted that standard round shot had a tendency to jam up in the bore when used with extreme charges or when stacked on the bore.  So he used a special dumb-bell shaped projectile.  None of the guns lasted past 38 fires:

Although extreme tests, these results were not consistent and not promising. But this did set the maximum proof test at three pounds of powder with sixteen balls.

So Wade tested another four guns.  Again, each handled a bit differently in casting:

  • No. 5 – cast after the iron was in fusion for half an hour.
  • No. 6 – cast after the iron was in fusion for one-and-a-half hours.
  • No. 7 – cast after the iron was in fusion for three hours.
  • No. 8 – cast after the iron was in fusion for three-and-three-quarters hours.

The guns suffered through similar tests.  Wade offered this table of the results:

Of the batch, No. 7 survived the tests. In his summary, Wade offered few conclusions, but did compare the test gun’s endurance with those of European origin tested three years earlier.

Wade continued tests with different castings in April 1844, this time of simple iron bars, at different temperatures and fusion times.  In this report he noted results of tensile strength.  Through the remainder of 1844, Wade continued experiments with heavier iron guns in production at Alger’s foundry and measurements of the specific gravity of the iron.  Late in the year, Wade subjected two old 18-pdr guns and the surviving No. 7 iron 6-pdr to hydrostatic tests to determine breaking points.

Alger continued to produce iron guns for experiments after those two batches.  Registry receipts indicate Wade accepted a ninth iron 6-pdr from Alger in 1844.  Perhaps Wade used that gun in a similar set of tests, but I have found no record of such.   Alger delivered two more iron 6-pdrs in 1848 for testing, likely to the same pattern as the 1844 guns.  A surviving gun, with a 1854 date stamp, at Newport, Rhode Island, produced to a similar form as the 1844 guns is rifled to the James system.  Apparently the “form” was good enough for repeated use.

Granted, these test guns were not intended for the field.  But the results of these tests provided the ordnance officers and cannon foundries with important data on which to build conclusions.  Certainly Wade’s experiments aided later heavy guns that saw service in the Civil War.  But in some small part, experiments with metal handling lead to procedures which gave the Parrott field guns the endurance to handle the pressure of rifled projectiles.

Steps along the way to build a better cannon.