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.

Balloons and Artillery at Dr. Gaines Farm

One of Civil War Trust’s latest preservation efforts is a large parcel of property, covering 285 acres, at Gaines Mill, Virginia.  The targeted ground is that over which General James Longstreet’s men attacked on June 27, 1862.

But like many locations in Virginia, the site was not a “one event” spot.  A month earlier, Federals occupied positions around Dr. Gaines farm.  At that time the balloonist made an appearance, as the Federals worked across Chickahominy  Creek at New Bridge.  An article on Civil War Trust’s site briefly discusses this skirmish with regard to the aeronaut activities.  Thaddeus Lowe established the “Balloon Corps” station on Gaines Farm in late May.  On May 23, batteries of the 2nd US Artillery, from the Army’s horse artillery, deployed in the same area.   Company A, 2nd US Artillery, under Captain John C. Tidball, shelled Confederate positions and received some direction from the balloonists.

In his official report on the action, Tidball wrote:

I have the honor to report that about 12 m. on the 23d instant my battery was ordered from its camp near New Bridge, over the Chickahominy River, for the purpose of shelling the ground occupied by the enemy in the vicinity of that bridge.

The pieces were placed in battery near the mansion of Dr. Gaines, and from there opened a steady and well-directed fire on the point indicated. The enemy made no reply, but, from the report of those in the balloon, fled from their position. After firing 93 rounds the battery was withdrawn, and a few minutes afterward started on its march toward Mechanicsville. A few rods after the head of the column, of which the left section of my battery constituted an advanced portion, had passed the bridge over Bell’s Creek, several cannon-shots were fired by the enemy from pieces on the eminence immediately in our front…. (OR Series I, Volume II, Part I, Serial 12, page 656).

Sort of a one-sided action, almost a routine action in many regards.  But Tidball’s mention of the balloon is worth analysis.

There are many mentions of “indirect” fire employed during the Civil War, or more specifically – “spotted” fire.  Contrary to our American pride, this style of fire control was not developed during our mid-19th century conflict, but rather dates back practically to the concept of siege weapons (in other words ancient stuff).  However the use of balloons, signal flags, telegraph, and other technologies came into play during the Civil War.

The question does arise why the combatants did not make more use of spotted fires.  Well there were some problems with technology.  The oft cited issue involved the lag in communications.  However one can imagine Lowe, a few hundred feet above Tidball’s guns, shouting down, “… a little to the left…” or “… give it one more turn of elevation….”  But at best Lowe could only offer a description of where the shot fell.  He could not aid the direction of the next shot.

You see, the real problem was not with communications, but with the guns themselves.  In order to “spot” a round, the observer and gunners must have some reasonable way to have the projectile fall in a predictable manner – in other words, consistent shot pattern.  Civil War artillery lacked recoil dampening or compensating systems.  The projectiles used rudimentary time fuses which were prone to failure.  The projectiles themselves, both rifled and smoothbore, were apt to take erratic ballistic courses.  And none of this took into account the effects of wind, weather and temperature.  Putting two successive rounds in the same spot required luck in addition to the skill of the gun crew.

Predicted fire would have to wait a few more decades until recoil systems, better projectiles and guns, advanced firing tables, and proper weather reports would enable gunners to place rounds on a target with some degree of regularity.  At that point, “spotting” was not only possible, but required!

Sunbury’s Confederate Iron Guns

When showcasing the Confederate iron 6-pdr field guns from Tredegar I featured the guns at the Brawner Farm on the Second Manassas battlefield.  Another place to view a set of these iron smoothbores is Sunbury, Pennsylvania at the foot of the Northumberland County Civil War memorial.

PA Trip 26 Nov 11 124
Northumberland Civil War Memorial

Because the iron fence prevents “walk around” I’ll still suggest Manassas for students who wish to examine the guns closely.  But Sunbury is a good side trip for those traveling down Highway 15 (on the way to… say… Gettysburg?).

Of the three guns, only one has visible markings to speak of.

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6-pdr Iron Field gun - Tredegar #1486

The muzzle on this gun displays the familiar Tredegar foundry number mark.  In this case #1486.

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Muzzle of Tredegar #1486

On the breech, just in front of the vent, is the weight stamp of “918”.

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Breech of #1486

Records show that Tredegar cast #1486 on April 9, 1862.  The gun is among four others sold to the Confederate Army on May 10.  The others being #1485, #1487, and #1477.  These appear on the same invoice as the 3-inch Rifled Field Gun #1464.  Certainly the smoothbore #1486 at Sunbury and the rifled #1464 at Gettysburg share the same outward appearance from the flattened knob to the straight muzzle.

However the other two 6-pdrs at Sunbury have the older style knobs and muzzle swells.  While there are no markings to confirm these as Tredegar guns, the form matches that of the earlier 6-pdr iron guns (and 3-inch rifles for that matter).  Good coats of paint hide the years of weathering.

PA Trip 26 Nov 11 074
Shiny 6-pdr Field Gun, Presumed Tredegar

One of these has a tall, and relatively undamaged, muzzle sight post.  The neck of the knob has cut-outs similar to those seen on Tredegar rifled guns.  Another indication of the connection between 6-pdr and 3-inch iron gun patterns.

PA Trip 26 Nov 11 078
Breech of Unmarked 6-pdr

The last of the three displays scars and scuffs under the otherwise good paint.  It also lacks any front sight fixtures.

PA Trip 26 Nov 11 080
Unmarked 6-pdr at Sunbury, Presumed Tredegar

There are other guns at Sunbury’s monument.  Two 8-inch Siege Mortars of Model 1861 sit in between the field guns.  While stopped with tampons, the markings are easy to read.  No doubt the subjects for a future post!

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8-inch Siege Mortar Model 1861

However there is one more 6-pdr at Sunbury, also an iron gun.  But this piece was likely cast well before the Civil War.

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Unknown 6-pdr at Sunbury

The external form resembles guns cast in the first decades of the 19th century.  While this gun has rimbases for the trunnions, it also has a key-hole vent.  Certainly fodder for speculation and perhaps another post.

But as nice as these American iron cannons are, I must admit the highlight of Sunbury’s downtown display is this piece:

PA Trip 26 Nov 11 109
77mm FK16 German Field Gun

This gun, a German 77mm FK16, came home with World War I veterans and speaks to another time and another place in history.

How to Raise a 25-Ton Cannon: Elevation System for Rodman Guns

Yesterday I covered the mechanical operation of the elevating system on pre-Civil War columbiad gun carriages.  This type of elevating gear worked for columbiads, seacoast howitzers, and even a few Navy shell guns that entered service from the 1840s to the close of the 1850s.  Almost all Confederate columbiads used the system.  Even the first batches of Rodman guns used the system.

However the weight of the larger Rodman guns exceeded the practical limits of the Columbiad’s system. The chief problem was the preponderance required to keep the weighted on top of the elevating gear (specifically the pawl).  While this ensured the elevation remained true during firing, during handling the preponderance made the gun crew’s work difficult if not outright dangerous.  The 15-inch Rodmans entering service in 1861 exceeded the limits of what a reasonable gun crew could manage – 1,200 pounds.   So an alternative system came into use.

To my knowledge, no documentation details the experiments and design of this modified elevation system.  The Rodman guns arrived on the scene about the same time as wrought iron carriages for seacoast guns.  However the early diagrams of Rodman guns on iron carriages seems to show the older style elevating system.

At some point that elevating gear gave way to this:

Fort Foote 1 Mar 08 138
Breech of 15-inch Rodman at Fort Foote

The post, sometimes referred to as a ratchet post, replaced the elevating screw, elevating box, and pawl of the earlier arrangement.  Instead, the crew simply inserted the elevating bar directly into the post and against the sockets on the breech face.  With that the crew could lever the gun’s breech up or down.  Here’s how the manual of service described the action:

No. 4 [crewman] mounts upon the chassis and, embarring through the ratchet-post with the elevating-bar, raises or lowers the breech as directed by the gunner.1

Very simple.  Angle the gun appropriately.  Just as seen in this posed photo from Battery Rodgers, Alexandria, Virginia.

The bar had a squared off head to fit into the sockets on the gun’s breech.

Fort Trip 26 Mar 11 107
Close up of Sockets on 15-inch Rodman

The post sat just a few inches from the breech face, but that was all the room needed.

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Breech Clearance

What did Archimedes say about just needing a place to stand?  And notice the post does not touch the breech.  And there is no elevating screw or other point supporting the breech.

Fort Trip 26 Mar 11 130
Inside of the Post

Inside the post are several slots with the open ends towards the breech.  Presumably these engaged with pins or other fittings on the elevating bar.  The orientation would allow the bar to remain firmly seated while the crew worked.

Now how exactly was this an improvement on the older ratchet-pawl system?  Well take note of the 15-inch gun in profile.  How many points does the gun itself touch the carriage?

Fort Trip 26 Mar 11 140
15-inch Rodman - Alger #1

Give yourself a gold star if you said two points.  Only the trunnions touch the carriage (recall the spacing of the post above).  So even after 150 years, this 25 ton gun balances on the trunnions.  After the 15-inch Rodman prototype, and small batches of 8- and 10-inch models, all Rodman guns were cast “without preponderance” by moving the trunnions just a few inches back.  So instead of working against 1,200 pounds of preponderance while elevating the piece, the No. 4 man needed only to press the lever up or down.

But with that careful balance, I’ve often wondered just loading the piece would serve to drop the gun off balance.  The addition of a 450 pound solid shot might create a giant, dangerous teeter-totter.  Although the manuals do not indicate such, retaining the elevating bar in place during firing might prevent the fall of the gun.  The orientation of the slots in the post would allow such, by not allowing the bar to fly loose when the gun fired.  And at least one photo shows the bar remaining in place with the gun in position, this one again credited to Battery Rodgers.

Another photo captioned as Battery Rodgers shows a gun brought back to a stowed position.  If you look close, laying behind the elevating post is the elevating bar.

So, for these big Rodmans, the crew had a much easier job with elevation as compared to the older Columbiads.  Still, ease of use must be taken in context.  The rate of fire for a well drilled crew on a 15-inch Rodman was one round every five minutes.2 Even without preponderance on the breech, crews moved slowly around these heavy iron monsters.

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Notes:

  1. John C. Tidball, Manual of Heavy Artillery Service: For the Use of the Army and Militia of the United States (Washington: James J. Chapman, 1891),   Page 114.
  2. Ibid, Page 127.

How do you elevate an seven-ton columbiad?

So you have one of those 15,000 pound 10-inch columbiads or 9,000 pound 8-inch columbiads mounted (which was no small feat to begin with).  The enemy fleet is threatening to sail up the channel.  How the heck to you point that big gun on the target?

The Bellona 8-inch Columbiad at Fort Darling is a good study to answer that question.

10 July 11 853
Bellona 8-inch Columbiad at Fort Darling

Pointing1 the gun required two variables – traverse and elevation. The gun crew positioned the gun in traverse – the horizontal direction to point the gun – by turning the carriage itself.  The Fort Darling gun sits on a center pivot barbette carriage.  Handspikes fixed to sockets on the rear of the carriage rails allowed the crew to turn the gun 360°.  For front pivot barbette carriage, the crew worked with a reduced traverse, but the concept was the same.  While the crew had to exert themselves to move the weight of gun and carriage, if well maintained, the wheels and rollers allowed free movement.  Traverse of the large columbiads differed little from the smaller seacoast guns on similar carriages.

10 July 11 844
Lower Angle View of the Carriage showing the Rollers and Wheels

The horizontal angle, or elevation, however involved movement of the piece against the trunnions.  In the case of smaller guns, an elevating screw worked against the bottom of the breech, to raise or lower the back end of the gun.  Excess weight, or preponderance, on the back end of the gun ensured the piece laid on the head of the elevating screw.  This mechanism worked fine for weapons ranging from field artillery and seacoast guns, which were not elevated beyond 5°.  For columbiads, where elevations might reach 40°, the breech elevation screw would be too long for practical use.

So for columbiads, the Ordnance Department figured out a different, more elaborate, means to elevate the piece.  Joseph Robert’s Hand-book of Artillery explained this system in detail:

The elevating arrangement consist[s] of an elevating-screw, working into a screw-bed, which slides in a vertical box, and carries on top of it a movable pawl to fit into the notches cut in the breech of the gun, in order to give considerable elevations.  For the purpose of transferring the pawl from one notch to the next, it has a slit in it, through which the elevating bar is passed, and the gun supported by making use of the edge of the elevating-box as a fulcrum.  This arrangement is over the rear transom.2

The mechanism used four components – elevating screw, elevating box, a pawl (or finger), and an elevating bar.  Three of those four are seen below on the Fort Darling columbiad.

10 July 11 860
View of Elevating Mechanism

The elevating screw, at the bottom of this view, worked inside the elevating box.  The box also housed the pawl, which sat on top of the elevating screw.  As the crew worked the elevating screw, the pawl moved up and down within the elevating box.

10 July 11 849
Breech of Columbiad showing Pawl against Ratchets

The movement of the pawl would apply or relieve pressure on the breech of the columbiad.  To provide the pawl a purchase against the breech, the pawl fit into a series of notches or ratchets in the breech.  This was of course fine to elevate the gun through about 5°, but the mechanism needed more play to work the required 40°.  That’s where the handle on the back of the pawl came into play.

10 July 11 859
Pawl and Elevating Box

When more than 5° of elevation were required, the crew placed the elevating bar (what we might call a pry bar today) against the breech.  The channel on the top of the elevating box provided a fulcrum for the elevating bar, which was also fed through the open eye in the pawl.  This allowed the crew to relieve pressure on the pawl.  One of the crew would then remove the pawl from the ratchet by using the handle (note the hinge at the base of the pawl seen inthe view above).  If needed, the elevating screw worked to reposition the pawl height.  Then the crew-man would set the pawl into the appropriate ratchet.

For operation, here’s how the Instruction for Heavy Artillery (1850) described the process for elevating a columbiad:

The gunner withdraws the priming-wire; inserts the pawl of the elevating machine in the proper notch by means of the elevating bar, and with the breech-sight gives the required elevation; No. 4 [crew-man] turning the handle of the screw according to his direction.

The moment the piece is correctly pointed he rises on the left leg, and gives the word READY, making a signal with both hands….3

The setup at Fort Darling is a bit “over elevated.”  While this allowed me to photograph the details, the arrangement is not how the mechanism would appear in action.  To better appreciate the setup, consider this wartime photo of a 10-inch Columbiad at Fort Darling.

10-inch Columbiad at Fort Darling

If you look close, there is an elevating bar to the left of the elevating box.  The pawl is set against the bottom ratchet, which is the right position for point blank firing.

So all that work would allow the gunner a view something like this:

10 July 11 858
Aiming down the James River

Busy work for a gun crew in the heat of battle, don’t you think?  Keep in mind that for every shot, the crew would return the gun between zero and  5° elevation to facilitate reloading. Worse yet, since the columbiad elevation system still required preponderance to seat the gun against the pawl, the crew had a lot of weight to deal with.  For an 8-inch that was 635 pounds.  For a 10-inch that was 740 pounds.4  Not a trivial matter.

Early Rodman Guns used the same elevation system, with some reduction of preponderance.  For the first batches of 8-inch Rodmans, the preponderance stood at 350 pounds.  The 10-inch Rodman prototypes had a 519 pound preponderance.  However, the 15-inch Rodman prototype, the most favored anti-ship weapon in the arsenal, strained the muscles of the crew with its 1,200 pound preponderance.5 Clearly the system had reached its physical limitations.  So the Ordnance Department devised an alternative.  I’ll turn to that next.

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Notes

  1. The verb “pointing” appears in most pre-war and wartime manuals.  Pointing implied the gun was oriented towards a target, as was the case with fire control practices of the time.  The verb “aiming” came into wider use for artillery towards the end of the 19th century, as gunners would use reference points to predict and direct the shot onto a target.
  2. Joseph Roberts, The Hand-book of Artillery: For the Service of the United States (Army and Militia) (New York: D.Van Nostrand, 1860), page 137.
  3. Instruction for Heavy Artillery (Washington:  Government Printing Office, 1862), pages 70-71.
  4. The Ordnance Manual for the Use of the Officers of the United States Army, edited by Theodore T. S. Laidley (Philadelphia: J.B. Lippincott & Co., 1862), page 20.
  5. The Ordnance Manual for the Use of the Officers of the United States Army, edited by Theodore T. S. Laidley (Philadelphia: J.B. Lippincott & Co., 1862), page 18.

Another Paperwork Trail: Bellona 8-inch Columbiads

You might recall a couple of 8-inch guns  from St. Augustine from earlier in the Confederate Columbiad thread.

St. Augustine 1 Aug 11 515
Bellona 8-inch Columbiad No. 29

The muzzle stamp very clearly identifies this gun as registry number 29.

St. Augustine 1 Aug 11 509
Muzzle Stamp for #29

But you may recall that I took exception to the plaque at the base of the gun mount.

St. Augustine 1 Aug 11 510
Plaque Mentioning the Gun's Service

As I said at the time, with a production year of 1861, the gun was certainly not in St. Augustine before the Civil War.  Indeed, Federal reports indicate that prior to Florida’s secession the only 8-inch weapons at Fort Marion were old seacoast howitzers, not “proper” columbiads.

But what about during the Civil War?  Did the Confederates send this gun, and it’s mate, to St. Augustine?  If so, there should some notation of 8-inch Columbiads.  Unfortunately, the records of Bellona Foundry are incomplete at best.  But there is one invoice dated October 20, 1861 that mentions registry number 29.

The bill records four 8-inch Columbiads numbering 29, 30, 31 and 32 shipped to three different locations on October 21 (see the remarks on the right side).    Notations mid-way down indicate, “by direction of Lieut. Col. Gorgas Chief of Ordnance,” the destinations of those four guns:

  • One to General John Magruder at Yorktown, Virginia.
  • One to General Richard Gatlin at Fort Macon, North Carolina.
  • Two to the commander of defenses at Cedar Key, Florida.

Unfortunately the records do not indicate which gun went where.  But each of these localities were the site of military action in the winter and spring of 1862.  The USS Hatteras raided Cedar Key on January 16.  Fort Macon fell to General Ambrose Burnside in April.  Yorktown fell after a long, but somewhat cumbersome, siege in early May.

There’s a lot of room for speculation regarding these guns.  Photographs from Yorktown show guns very similar to Bellona #29 in the Confederate works.

But look close.  Those are wooden carriages.  Recall that #29 has short trunnions used on iron carriages. The nearest columbiad in the photo has long trunnions.  We might debate the shadows on the trunnions of the second gun,  however.  As for Fort Macon and Cedar Keys, I have no specific returns of those defenses to work from. So my speculation on those points must end there.

A Federal naval force from the USS Walbash, under Captain C. R. P. Rogers, landed at St. Augustine on March 11.  In his report, Rogers stated the Fort Marion contained three 32-pdr guns and two 8-inch seacoast howitzers, along with “a number of very old guns….” (Report of Captain Rodgers, Naval ORs, Series I, Volume 12, page 595-7).   Such would exclude presence of the 8-inch Columbiads from the Bellona invoice. 

Given the invoice and Captain Rogers’ report, the presence of Bellona #29 as part of the Confederate defenses of St. Augustine is unlikely.  And the same can be said for #27 on the other side of the Plaza de la Constitución.  The weight of evidence points to the capture of these two guns, perhaps early in 1862.  If so, these guns may have arrived in St. Augustine during the war years when Fort Marion was used as a depot.  Just as likely the guns arrived after the war for use in memorials.  But the documentation rules out active use of the Confederate Columbiads at Fort Marion.

So should someone change the plaques?  I say no.  Let’s keep this bit of trivia between us as some “insider” factoid.  No need to pull the rug from underneath the quaint, nostalgic, undocumented story about these columbiads.