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 [decorative delimiter] Class of 1841

Vol. II

(Born Ind.)

Thomas J. Rodman

(Ap'd Ind.)


Thomas Jackson Rodman: Born July 31, 1816,​a1 Salem, IN.

Military History. — Cadet at the Military Academy, July 1, 1837, to July 1, 1841, when he was graduated and promoted in the Army to

Bvt. Second Lieut., Ordnance, July 1, 1841.

Served: as Asst. Ordnance Officer at Allegheny Arsenal, Pa., 1841‑42, being detached to Richmond, Va., May 14 to June 28, 1845, for the preparation of machinery for testing gun metal, and Oct. 27 to Dec. 27, 1845, to supervise the manufacture of cannon, — at Boston, Mas., Sep. 16 to Nov., 1846, mounting and experimenting with Indicates a West Point graduate and gives his Class.Bomford's  p67 12‑inch Columbiad, — and at Fort Pitt Foundry, Pittsburg, Pa., most of

(First Lieut., Ordnance, Mar. 3, 1847)

1847, supervising the manufacture of cannon; as Ordnance Officer, 1848, during the War with Mexico, at Camargo and Point Isabel Depots; as Asst. Ordnance Officer at Allegheny Arsenal, Pa., 1848‑50, 1850‑52, 1852‑53, 1853‑54; at Iron Mountain and Pilot Knob, Mo., Feb. 6 to Apr. 14, 1850, examining iron and furnaces; in command of Allegheny Arsenal, Pa., Feb. 27, 1854, to Mar. 14, 1855; — and of Baton Rouge Arsenal, La., Mar. 28, 1855, to June, 1856; at Pittsburg, Pa., June 6, 1856,

(Captain, Ordnance, July 1, 1855, for Fourteen Years' Continuous Service)

to Jan. 6, 1857, testing experimental cannon; as Asst. Ordnance Officer at Allegheny Arsenal, Pa., Jan. 6, 1857, to May 8, 1859, being detached, at intervals, to fix programme of Experiments with cannon, — experimenting on gunpowder, and determining proper form of cannon, — testing carbines, — and inspecting and fixing the quality of iron; and in command of Watertown Arsenal, Mas., May 12, 1859, to Apr. 12, 1861, continuing his experiments on metal for cannon, form of guns, gunpowder, etc., the results of which were published in 1861, in a valuable work, entitled "Report of Experiments on Metals for Cannon, and Cannon Powder."

Served during the Rebellion of the Seceding States, 1861‑66: in command of Watertown Arsenal, Mas., Apr. 12, 1861, to Aug. 3, 1865, being

(Major, Ordnance, June 1, 1863)

on various detached duties, 1859‑65, particularly the supervising of the casting and testing the first 15‑inch Columbiad, 12‑inch rifled gun, and 20‑inch smooth-bore, and supervising the casting of all Projectiles and Ordnance (with hollow core and cooled from inside to outside, as invented by himself), for the U. S. Ordnance Department.

Bvt. Lieut.‑Col., Mar. 13, 1865,
for Faithful, Meritorious, and Distinguished Services in the Ordnance Department.

Bvt. Colonel, Mar. 13, 1865,
for Faithful, Meritorious, and most Distinguished Services
in the Ordnance Department.

Bvt. Brig.‑General, U. S. Army, Mar. 13, 1865,
for Faithful, Meritorious, and Distinguished Services in the Ordnance Department.

Served: in command of Rock Island Arsenal, Ill., Aug. 4, 1865, to

(Lieut.‑Colonel, Ordnance, Mar. 7, 1867)

June 7, 1871; and as Member of Ordnance Board on Seacoast Rifled Cannon, carriages, and other Ordnance matters, Dec. 12, 1867, to Jan. 4, 1868, — of Board to examine Ordnance Officers for promotion, Jan., 1868, — of Board to examine Major Indicates a West Point graduate and gives his Class.Whittemore's modification of the Springfield rifle, Feb., 1868, — of Board to test Beaupré's system of constructing cannon, Aug. 19 to Sep. 5, 1868, — of Board to consider the proto­col of the International Military Commission relative to the using of certain War Projectiles, Jan. 25 to Feb. 3, 1869, — of Board to examine Col. Indicates a West Point graduate and gives his Class.Benton's plan of moving and manoeuvring heavy guns, Jan., 1870, — of Board on supply of Ordnance and Ordnance Stores to U. S. service, May, 1870, — and of various Ordnance and Artillery Boards, 1865‑71.

Died, June 7, 1871, at Rock Island, Ill.: Aged 53.

Buried, Rock Island National Cemetery, Rock Island, IL.

Biographical Sketch.

Bvt. Brigadier-General Thomas J. Rodman was born, July 30, 1815,​a2 at Salem, Ind., where he received an education such as occupation  p68 on his father's farm permitted; and, if not liberal in book knowledge, was more than compensated by the full development of his fine physique and robust constitution. When he entered the Military Academy he was of the maximum age, and fully alive to the advantages there afforded for his intellectual growth. By hard study, and close attention to every duty, he was graduated, July 1, 1841, seventh in an excellent class of fifty-two members. Upon his promotion in the Army to be a Second Lieutenant of Ordnance, he was ordered to Allegheny Arsenal at Pittsburg, Pa., where he devoted much of his after life to those patient and laborious investigations which built so well and so high his enduring professional monument. Entering at once into every practical detail of the workshops, and carefully studying their complicated machinery, he rapidly acquired a mastery of the fundamental elements of his vocation, and soon, in the crucible of his inventive brain, separated the dross of false principles from the pure truth of new and brilliant discoveries in metallurgy and artillery.

He was detached to Richmond in 1845 to prepare machinery for testing gun-metal, and then to supervise the manufacture of cannon. Here in the casting of heavy ordnance, the porous condition of the metal, and "the sinking head," at once attracted his attention, and convinced him of the error in the idea of cooling the castings of guns from the exterior inwards, thereby tearing apart, instead of consolidating, the metal, — an opinion confirmed by his later investigations of the laws of the strains to which guns, when fired, are subjected. To correct these errors, he proposed to wrap in successive layers a peculiar-shaped wire with a constant tension around a solid wrought-iron core, in which to form the bore of the gun. But, as such a design involved almost insuperable difficulties, his inventive genius devised a new plan which led to his fame and fortune — that of cooling the casting from the interior outwards. By this new method he brought each successive layer of metal as it hardened, like contracting hoops of iron, more and more firmly binding together the whole mass, thus giving it a maximum strength to resist the expansion of the powder-charge acting from the interior outwards. After various cautious trials he succeeded in safely introducing a constant stream of cold water, through an iron pipe, to the bottom of the core-barrel, whence it rose and flowed over the top to be carried off. The success of his mode of cooling being established, eight pairs of guns were cast of the same metal in the same dimensions, one set by the old method of cooling, and the other on the Rodman principle. It is almost needless to add that the latter in every case, upon the severest trials, proved their vast superiority over the former.

"The advantages of this system," says Colonel Indicates a West Point graduate and gives his Class.Laidley in a very interesting and able sketch of Rodman as an ordnance officer, "are not confined to superior strength. The hollow cast guns have a harder and more close-grained metal for the surface of the bore, and it resists better the erosion of the gas and the action of the projectile upon it; and, what is of great importance in times of emergency, when despatch is important, the time of cooling the gun is much diminished, and the capacity of the foundry for work greatly increased. Notwithstanding these advantages, and the oft-repeated proof of its superiority, so great was the prejudice to be overcome, that it was only by dint of persistent effort that this mode of casting guns was adopted in 1859, some fourteen years after its first conception."

During our War with Mexico, Rodman was very usefully employed, — in 1846, mounting and experimenting with Colonel Bomford's twelve-inch Columbiad, the monster gun of its day; in 1847, supervising the manufacture of cannon at Fort Pitt foundry; and, in 1848, in charge of Ordnance Depots on the Rio Grande at Camargo and Point Isabel.

 p69  Till his promotion to a Captaincy, July 1, 1855, he was mostly engaged at Allegheny Arsenal on his various ordnance duties, and at Pilot Knob, Mo., in examining iron and furnaces.

From this time till the beginning of our Civil War, Capt. Rodman was on duty at Allegheny and Watertown Arsenals, experimenting on metals for ordnance purposes, determining the proper forms of cannon, improving gunpowder, etc., the results of which were published in 1861, by the Ordnance Department, in a valuable volume, entitled "Reports and Experiments on the Properties of Metals for Cannon, and the Qualities of Cannon-powder." This great contribution to the science of Gunnery reflects the highest credit upon our Army and country; is invaluable to the artillerist and metallurgist; placed Rodman in the forefront of original investigators; and gave a proud name to the distinguished Corps of which he was the shining star.

"The cause of failure of our heavy ordnance," says Col. Laidley, "was found in their defective model, the form of chamber, the mode of casting, and the improper powder used in them. A formula was worked out by which to shape the exterior model of all our guns, a formula based on the law of the varying strain along the entire length of the bore, and disposing of the metal according to this law, something which had never before been attempted. The strain on the gun from different charges of powder and projectile was determined, as well as that from the same charge of powders differing in density and in size of grain. This was something which had never been attempted, and how to accomplish it was not an easy task. But Captain Rodman's resources were equal to the undertaking. The information was of great importance, and his inventive faculty readily devised the means for its determination in the 'pressure piston' known under his name. The results given by this instrument are of such value in artillery that all of the principal European nations use it, or a slight modification of it, and in firing unusual charges the pressure resulting therefrom is now always a point to be noted. From these experiments was deduced the principle, which is now adopted generally, that powder must be made to suit the gun in which it is used; for large and moderately long guns we must have a large-grained, dense powder. But Capt. Rodman went a step further. He observed that the law of the evolution of gas from a charge of powder in the state of grains is just the reverse of what it should be in order to give the greatest velocity to the projectile with the least strain to the gun. To impart a rapid motion to any heavy body we first commence to move it slowly, and gradually increase the force as the inertia is overcome. The same course is necessary in giving motion to a heavy projectile. If the force be applied too suddenly before the ball has had time to yield to it, there is danger of bursting the gun. When a charge of grain powder is inflamed, the burning surface is the greatest at the first moment of ignition, and decreases rapidly as the inflammation progresses. The evolution of gas is therefore greatest at the first moment of inflammation, and diminishes rapidly as the burning continues. This brings a great strain on the gun at the first instant of discharge, from the suddenness of the application of the force, without a corresponding effect on the velocity of the projectile. By way of correcting this erroneous constitution of the powder, Capt. Rodman proposed to press such as was intended for heavy guns into large prisms with a series of small cylindrical holes parallel to their axes and the axis of the gun. The inflammation would then commence on the surfaces of these cylindrical holes, and the evolution of gas at first would be small, but as the burning continued the surfaces on fire would rapidly increase; the impulse to the projectile would be gradually increased, and the motion accelerated till the ball reached the muzzle.  p70 Thus a high velocity would be given to the shot without subjecting the gun to an excessive strain. Powder made in this form was tried with remarkable results. Experiments with it were witnessed by foreign officers, and it has been adopted since by both the Russian and Prussian governments, under the name of prismatic powder. 'Rodman Powder' would have been a better name, as recognizing the source from which it was taken without offer of compensation of any kind. Capt. Rodman improved the ordinary powder for large guns by pressing each grain into exactly the same shape, resembling a double convex button. The English Government, long incredulous as to the advantages to be derived from large powder, has at length adopted this improvement, modifying slightly the shape of the grain, and now sings loudly its praise under the name of 'pebble powder.' "

Rodman, not content with all he had done for perfecting guns and ammunition, next applied himself to correcting the immemorial practice of placing the trunnions of guns so as to give a breech preponderance of weight, instead of through the centre of gravity of the piece, thus preventing shocks on the elevator. Notwithstanding the sneers of his seniors that his balanced-gun idea was the result of an unbalanced brain, he persevered till he successfully accomplished an entire change of our system.

From Apr. 12, 1861, when began the bombardment of Fort Sumter, till Aug. 3, 1865, when the Civil War had ended, Rodman was not allowed to share the honors of the tented field, though, for the success of our arms, he was straining every nerve, day and night, to provide at Watertown Arsenal the munitions of war. Without even a Sunday's rest and recreation, he so assiduously labored on, in season and out of season, that in 1864 he nearly paid the forfeit of his zeal with his life. During this period he had become, June 1, 1863, a Major of Ordnance; and, for his devotion to duty during the Rebellion, was brevetted, Mar. 13, 1865, to be Lieutenant-Colonel, Colonel, and Brigadier General in the Army, for his "faithful, meritorious, and most distinguished services."

General Rodman, Aug. 4, 1865, was ordered to the command of Rock Island Arsenal, Ill. "This new station," says Colonel Laidley, "at once felt the influence of his enlarged views and his energy of action. A new plan for a combined arsenal and armory on a scale of colossal proportions was proposed, the appropriations obtained, and soon work was vigorously commenced to carry it into effect. The care and responsibility attending such work, and the incessant labor with which it was accompanied, particularly to one who attended so much to detail as he did, began to tell on a constitution already weakened by previous excessive labor, and he was warned by his physician of the absolute necessity of his taking a leave of absence for the sake of rest and recreation. But he was interested in his work, took a pleasure in seeing his plans carried out in his own way, and under his own supervision; he was busied about that which was to be a monument to him for ages, to tell of his ability in planning and his skill in constructing, and he neglected to heed the wise counsel until it was too late. Fairly broken down by the heavy weight he had been carrying, his strong physique, which with care might have lasted for many years to come, yielded to the incessant demands made upon it, and when only a little past the prime of life his career of usefulness was abruptly terminated, and his work brought to a premature close." His untimely death took place, June 7, 1871, at Rock Island, at the early age of fifty-three, four years after his promotion to be a Lieutenant-Colonel of his Corps.

Fortunately for our country, Rodman's improvement of the material of our artillery and melioration in the casting of heavy ordnance took place before our civil contest began, when the English navy regarded the eight-inch gun as the heaviest and most power­ful that could be safely used on shipboard.

 p71  England, ever aggressive towards weaker powers; considerate only of her advantages; anxious to avenge her failures in our Revolution and War of 1812; the ready supporter of that slavery she had imposed on America in the sixteenth century, and for which Hawkins was knighted by Elizabeth; and the opposer of our Free North by her titled, educated, and even religious classes, — had, through her power­ful press, arrayed all Europe, except Russia, against the Union. Well might the Southern Confederacy confidently expect foreign aid, both moral and material, in the establishment of her independence; more than over Big Bethel and Bull Run victories could she rejoice at belligerent rights granted her by both England and France; and on the tiptoe of hope might anticipate our foreign complications when we had blockaded the Southern ports, kept King Cotton at home, and seized the Confederate ambassadors on the "Trent."

During the existence of these critical circumstances, an event occurred of the highest import to our future, — the defeat in Hampton Roads of the Merrimac by the little Monitor, mounting only two eleven-inch guns. England at once saw the powerlessness of her wooden walls, and that even her mailed broadsides must go down before such power­ful artillery. All Europe was astounded at the brilliant achievement of Ericsson's "cheese-box on a raft;" but Rodman's fifteen and twenty inch guns were the powers behind materially shaping our after destiny. American artillery then was as much advanced as it is now behind all Europe, and commanded the respect of our secret foe, who arrogated the title of mistress of the seas.

General Rodman, who had thus been an important factor in the Civil War, was not only a scientific soldier, but was also an upright citizen and a large-hearted, noble-minded man. Brought up on a farm, constantly in the open air, and daily laboring with his own hands, his bodily powers were as fully developed in youth as were his mental in manhood. His was truly the mens sana in corpore sano. His capacity for work was prodigious, his energy most enduring, and his perseverance never flagged till the goal of his ambition was attained. He did not possess the quickness and flash of genius; rather a mind working slow and sure, never jumping at conclusions, but methodically examining and cautiously weighing every fact before crying Eureka. He always looked well into fundamental principles, took a comprehensive grasp of a subject, thoroughly sifted the wheat from the chaff, and by patient study became an admirable investigator. To all these qualities, so essential to the success­ful scientist, he added quick perception, fertility of invention, and originality and boldness in design. By these high faculties, happily applied to the service of his country, he "has acquired for himself a name which will be known as long as the history of artillery shall be written and handed down, and will be inscribed and honored along with those bright lights of ballistic investigation of the last century, — Rumford and Robbins." No man, in the tide of time, has done more for the progress of artillery science than our own Rodman.

Not only as a scientist and ordnance officer did he shine, but he was the light also of the family hearth and the social circle. He was the most genial of men; overflowed with rollicking fun; was exhaustless in humorous stories; and knew by heart every bright saying of Dickens and Thackeray, who were his favorite authors. With him, humor was as much the idol of his leisure moments as was science the idol of his hour of thought.

Thayer's Note:

a1 a2 July 31, 1816 is the date on his tombstone (q.v.).

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