MFR History of The Fort Pitt Works


Lieutenant General
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Managing Member & Webmaster
Apr 1, 1999
Martinsburg, WV
Among the many notable manufacturing establishments in Pittsburgh that might be alluded to with propriety, there is one that has attained a world wide reputation for its success in casting Heavy Ordnance, viz the Fort PITT Works. This cannon foundry was first established during the war with Great Britain in the year 1814, by Joseph McClurg, who was at that time the owner of a foundry, which supplied the ordinary iron castings needed by the inhabitants of a small town. It was situated at the corner of Fifth and Smithfield streets, on the ground which is now occupied by the United States Custom House and Post Office. It had supplied Commodore Perry with the cannon balls and grape shot used by his fleet in the memorable battle on Lake Erie, in September 1813.

Mr. McClurg then made a contract with the Secretary of the Navy for the manufacture of cannon and carronades, and immediately proceeded to erect a boring mill and machinery on the ground now occupied by the Fort Pitt Works, which was then in the open fields outside of the town limits. The boring mill was erected, and cannon were bored, and finished during the year 1814. The boring machinery was driven by horse power. At that period, all other cannon boring machinery in the United States was driven by water power, and as there were no waterfalls convenient to the Pittsburg foundry, and as steam power was then but little known, or used in the western country, the horse mill was of necessity resorted to. It was continued in use for three or four years, when the worn out blind horses were superseded by a high pressure steam engine of the plan invented by Oliver Evans. In 1815, the foundry and boring mill passed into the hands of the sons of Joseph McClurg, who soon after made a contract with the Secretary of War for the manufacture of a large number of cannon shot and shells, which were completed in 1816 and 1817, when further contracts were made and completed. At this period the largest cannon made for the military service was the 24 pounder, weighing about fifty two hundred pounds. In 1818, a Board consisting of experienced engineer ordnance and artillery officers was appointed by J.C. Calhoun, Secretary of War, to determine the caliber, form, and weight of all the cannon thereafter to be used in the military service. That Board in 1819, decided that the 24 pounder was the largest gun required, and none of larger size were cast until 1829, when the 32 pounder was adopted. Three years afterward, the 42 pounder weighing about eighty four hundred pounds, was added and this continued to be the maximum calibre for many years.

In 1831, Alexander McClurg and Major William Wade became the proprietors of the Pittsburg Cannon Foundry. Up to this date all the guns had been cast at the old foundry on the ground where the postoffice now stands, but in that year a new and larger foundry was erected on ground adjoining the boring mill, where the cannon were thereafter cast. The Works were enlarged, by adding machine shops for the manufacture of steam engines, and machinery, and for building locomotive engines, and railroad cars. And here the first locomotives ever made, west of the Allegheny mountain, were manufactured. In 1841, the establishment was purchased by Charles Knap, and WJ Totten, who had previously been engaged in managing the Works. They continued the manufacture of cannon shot and shells, and steamengines, and machinery, and in 1843 and 1844, they built and armed two iron steamboats, the Jefferson, and the Bibb, for the United States revenue service.

The military authorities, having given much attention to the subject of a further enlargement of cannon, Colonel George Bomford, Chief of Ordnance, had in 1839, and 1840, ordered the casting of two or three, 64 pounders, eight inch caliber, and one 125 pounder, ten inch caliber, at Alger's foundry in Boston. They were designed for experimental shell guns, and numerous trials were made with them in 1840 and 1842, with both solid shot, and shells. Up to this period shells had not been fired from long guns, but from mortars and howitzers only. These experiments proved that large heavy guns could be loaded and fired with ease, and rapidity, and that heavy shells could be safely fired from long guns with equal rapidity, accuracy, and range, as solid shot, and that they could be used on board ships at sea, with entire safety. These results were so satisfactory, that in 1842, both the eight inch, and the ten inch guns, were adopted as established calibres in the military service. After a further revision of their models in 1844, the weight of the eight inch was 9,250 pounds, and of the ten inch, 15,500 pounds. Further experiments in 1844, having more fully demonstrated the safety and the greater efficiency of these large guns, another still larger was proposed by Colonel Bomford, and accordingly a twelve inch gun, or 225 pounder was cast at Alger's foundry in July 1846. It was tried in the same year by firing it about one hundred times with heavy charges. The results were satisfactory in showing that a gun of the enormous weight of twenty five thousand pounds, fired with a charge of twenty eight pounds of powder, and throwing a loaded shell of one hundred and eighty pounds, three and a third miles, could be safely used and readily handled.

Up to this period, the method universally practiced in making cannon was to cast them solid, and to form the bore by drilling a hollow cylinder into the solid metal. Lieutenant Rodman, now General Rodman, who had in 1845, and 1846, been employed in superintending the casting of a large number of eight inch guns at the Fort Pitt Foundry of Knap & Totten, conceived that the manner of cooling such large masses of iron was injurious to the quality of the casting, as has been elsewhere alluded to, and it occurred to him that if the gun could be cast hollow, and be cooled from the interior the direction of the strains would be reversed and that instead of aiding the powder to burst the gun, they would increase the power of the metal to resist the internal force.

To test the accuracy of this theory, two eight inch guns were cast at the Fort Pitt Foundry in 1849. They were cast at the same time from the same melting of iron, and under like conditions in all respects as far as possible, except that one of them was cast solid, and cooled from the exterior in the usual manner, and the other was cast hollow, and cooled from the interior. After being bored, and finished, they were proved at the same time by continuous alternate firing with equal charges of powder, and shot, until both were broken. The number of fires endured by each, was about three to one, in favor of the hollow cast gun. This result although favorable to the theory, was not regarded as conclusive, and another similar trial of eight inch guns was made in 1851. In this the solid cast gun was broken at the seventy third fire, and the hollow cast gun endured fifteen hundred fires, and remains unbroken without any material visible injury.

In the same year, a pair of ten inch guns were cast, and tried in the same manner, and further similar comparative trials were made in the years 1856 and 1857, until six pairs in all of heavy guns were made and proved. The whole number of fires endured by the six solid cast guns, all of which were broken, was seven hundred and seventy two. The number of fires endured by the six hollow cast guns, only three of which were broken, was fifty five hundred and fifteen. The unbroken hollow cast guns after having endured fifteen hundred fires, each remain in apparent good order, and capable of much further service. The manifest superiority of the hollow cast guns, over those cast solid, being thus practically demonstrated the Secretary of War in 1859, ordered that all heavy guns made thereafter for the War Department, should be cast hollow and cooled from the interior on the plan invented by Captain Rodman.

The process of making the hollow cast guns, and the cooling them from the interior, is to place in the centre of the gun mould a watertight hollow core, the exterior diameter of which shall be a trifle less than the desired bore of the gun. While the liquid iron is passing into the gun mould, and surrounding the core, a stream of cold water is conducted by a separate pipe, down through the centre of the hollow core, nearly to its bottom, where it is discharged from the pipe, and then passes up through the annular space in the core, to the top of the mould, where it passes off in a heated state. While the cooling of the interior of the gun is thus accelerated, the cooling of the exterior is retarded by surrounding the gun mould with heated air, at as high a temperature as the safety of the mould will permit, or about eight hundred degrees. The water circulates through the interior of an eight inch gun at the rate of about two cubic feet per minute, and in the beginning its temperature is increased, while passing through about twenty five degrees. The circulation is continued, until the water passes out at the same temperature as that at which it entered, when the cooling is completed.

In 1851, after the decease of Mr. Totten, Major Wade again became a partner in the Fort Pitt Works, and associated with Mr. Knap, continued the manufacture of ordnance steam engines, and heavy machinery, until March 1858, when the whole establishment was entirely destroyed by fire. The rebuilding of the Works was immediately commenced, and in three months thereafter, the casting of cannon was resumed. In July 1858, Major Wade retired, and Mr. H.F. Rudd and N.K. Wade came into partnership with Mr. Knap. They had both been for several years previously engaged in conducting the operations of the Works.

In 1859, a further experiment for the enlargement of cannon was made, and in December of that year, a gun of fifteen inch bore, designed by Captain Rodman, was successfully cast at the Fort Pitt Foundry. Seventy six thousand pounds of iron were melted for this gun in three furnaces. The liquid iron passed in separate streams from each furnace into a common reservoir, where it intermingled and then passed to the gun mould. The gun was cast on a hollow core through which the water circulated at the rate of about six cubic feet per minute, for twenty four hours, when the core was withdrawn, and the circulation of water thereafter continued through the cavity left by the removal of the core for six days The quantity of water which passed through the interior of the gun was 3,595,300 pounds, nearly eighteen hundred tons, and equal to forty eight times the weight of the iron cooled. The additional heat acquired by the water in its circulation, and carried off from the interior of the gun, was ascertained to be seventy three per cent of all the heat contained in the melted iron when it entered the mould. The cooling of the gun occupied one week, and the time employed in lifting it from the pit, and in turning, boring, and finishing, it was nearly five months.

With the improved machinery since erected in these Works, a gun of this class may now be cast, cooled, bored, and finished complete all within twenty five days.

The gun when finished, was sixteen feet long, and forty nine inches, in diameter and weighed forty nine thousand pounds.

In May 1860, it was removed to Fort Monroe for trial and in the course of that year, it was fired five hundred times, with charges of thirty five to fifty pounds of powder, and with shells weighing from three hundred, to three hundred and thirty pounds.

The Board appointed to make these trials, composed of experienced engineer, ordnance, and artillery officers, reported that from the inappreciable injury which the gun had sustained in these trials, the rapidity with which it was manoeuvred, and fired, they were decidedly of opinion that the introduction of this class of guns was practicable and desirable.

The manufacture and trial of this fifteen inch gun, having proved entirely successful, Captain Rodman proposed in April 1861, that a gun of twenty inch bore, twenty feet long, and five feet diameter, weighing about one hundred thousand pounds, to throw a ball of one thousand pounds, be next manufactured and tried. But as the Rebellion which broke out just at this period, demanded the utmost efforts of all officers, and the resources of all the foundries for its suppression, the proposition could not then be considered.

Mr G.V. Fox, Assistant Secretary of the Navy, ordered a fifteen inch gun for navy service. It was cast at the Fort Pitt Works in June 1862, and was cooled in the same manner as the fifteen inch army gun. But in order to adapt it to service in turrets on shipboard, it was made about three feet shorter and weighed, when finished, forty two thousand and three hundred pounds. It was sent to the Washington Navy Yard, where it was tried by firing it with charges gradually increasing, from thirty to seventy pounds of powder, and with shot and shells, weighing from three hundred and thirty, to four hundred and thirty pounds each. It endured eight hundred and sixty seven fires, fifty of them with sixty pounds of powder, and was broken at last with a charge of seventy pounds of powder, and a shot of four hundred pounds. This severe test proving so satisfactory, it was decided to introduce guns of this class into service. And accordingly thirty of them were cast, and ordered on board the earliest turreted vessels constructed.

The great advantage of employing this larger class of guns in service was soon after demonstrated by the capture of the Rebel iron clad ram Atlanta, by the Weehawken, June 17th 1863. A single fifteen inch shot from the Weehawken broke the armor and wood backing of the Atlanta, prostrating forty men by the concussion, and wounding many more by the broken fragments of the iron, and the splinters. The safety and convenience with which this class of fifteen inch guns may be served, in both forts and ships, and the immense superiority of their destructive powers over all other cannon, heretofore used or known, having been thus practically established, Captain Rodman's proposition to make a twenty inch gun was considered and approved, and in 1863, the Secretary of War, Mr. Stanton ordered that one be made at the Fort Pitt Foundry, where the first twenty inch gun ever made was cast, in February 1864.

The rough casting for this gun was twenty five feet long, five feet and a half diameter, in its largest part. One hundred and seventy two thousand pounds of iron was melted for it. It was cast on a hollow core, and cooled from the interior in the same manner as the fifteen inch gun, before described. When bored and finished, it was twenty feet, four inches long, sixty four inches diameter, and weighed one hundred and sixteen thousand, five hundred pounds. It was sent to Fort Hamilton, New York, where it was mounted on an iron gun carriage, and tried in October 1864 by firing it five times, with charges of eighty, one hundred, and one hundred and twenty five pounds of powder, with a solid shot of one thousand and eighty pounds. It endured these fires without any perceptible injury.

In May 1864, a twenty inch gun was cast for the navy. Its length is about three feet less than the army twenty inch gun, and weighs ninety eight thousand nine hundred pounds. It was proved in April 1865, by firing it eight times with charges of sixty, eighty, and one hundred pounds of powder, and one solid shot of one thousand and eighty pounds, without injury. It has not yet been placed on board a ship.

Both of these twenty inch guns have thus far proved to be entirely safe, and preparations are now in progress for testing their durability, and for ascertaining the extent of their destructive powers against the strongest iron clad vessels and fortifications.

In the progress of the manufacture of cannon in the United States, the calibres have been enlarged from the twenty four pounder established in 1819, to the one thousand pounder, cast in 1864, an increase of forty five fold, in a period of forty five years, and but for its projecting trunnions, the largest gun of 1819 could be used in the gun of 1864 as a projectile, and be fired from it against an adversary, instead of shot or shells. It is not improbable that soon after a full trial of the twenty inch guns, others of twice their weight, will be cast and tried, since the method of interior cooling permits an indefinite extension of size.

To meet the suddenly increased demand for heavy cannon, shot, and shells, on the breaking out of the rebellion, in 1861 the Fort Pitt Works were much enlarged by adding new buildings, large furnaces, and heavy machinery, at a cost in all of about $240,000.

In 1863, Charles Knap again became the sole proprietor of the establishment, which is now one of the largest and most complete cannon foundries in the United States, or in Europe, as no other is known having the capability of manufacturing guns of such enormous size, or of producing any other kinds, with equal dispatch. It is now the oldest cannon foundry in the United States, having survived for more than twenty years, all others which existed when it was first established in 1814. Its proprietors had each, in continuous succession, been previously engaged in conducting its operations, thus inheriting whatever knowledge of the art had been acquired by the cumulative experience of their predecessors, for more than half a century.

The Works are built in the form of a hollow square, on a lot of ground, four hundred by two hundred feet, occupying the four sides of an entire city block, bounded on three sides by public streets, and on the other by the Allegheny river. The foundry contains six reverberatory air furnaces, capable of melting from twelve, to fifty tons each, and two cupalo furnaces, capable of melting twenty tons. If all of them were put in operation at the same time, they would be capable of melting one hundred and sixty tons of iron, and of making a casting of that weight in one single piece. There are fifteen gun pits in the foundry floor in which the moulds are placed vertically, on end when the guns are cast. Grate bars and ash pits are placed in the bottom of the pits, for receiving fuel with underground air flues, communicating with them for the purpose of heating the pits, while the guns are cooling.

The boring mill contains thirty one lathes, employed in turning boring, and finishing cannon, besides other special machines for dressing irregular curves, which cannot be accomplished by ordinary turning, or planing machines. The lathe constructed specially for the twenty inch guns, is sixty feet long, and eight feet wide, and weighs ninety thousand pounds. The boring tool does not revolve while the gun is boring, but advances in the line of the axis of the gun while the latter is revolving. When all the lathes are in full work, the weight of guns in revolving motion at the same time exceeds four hundred tons. The lathes have turned bored and finished complete eighteen heavy guns per week, viz two of fifteen inch, ten of ten inch, and six of eight inch, or at the rate of nine hundred guns per annum, requiring eleven thousand tons of melted iron.

The casting and boring apartments contain twelve large cranes, eight of which are worked by steam power. Four of the latter are capable of lifting, lowering, and moving horizontally, forty five tons each, and all the others from fifteen to twenty tons each.

By means of the steam power cranes and other machinery the heaviest guns are lifted out of the pits in which they are cast and moved from place to place through successive lathes and machines until they are finished complete when they are sent out of the Works and loaded on railroad cars for distant transportation by steam power alone

The importance of obtaining iron of the best quality for use in a cannon foundry has led to the employment of various methods for ascertaining its qualities by actual mechanical tests before using it in guns By comparing these tests with the endurance of guns subjected to an extreme proof trial by firing with powder and shot until they burst the mechanical tests indicate the qualities of iron most suitable for making the strongest guns The methods now practiced are first to examine the crude pig iron closely With the practiced eye of an experienced founder before it is put into the furnace Such pigs as are approved are then placed in the furnace and when melted small quantities are taken out at frequent intervals and cast into small moulds and as soon as the bars are cooled they are broken and the fractured surface is examined to ascertain the condition of the iron and to guide its further treatment in the furnace

Whenever a gun is cast a test bar from the same iron is cast in a separate mould which cools within a few hours and is tested before the next gun is cast When the gun head is cut off a sample is cut from that part of it which is nearest to the muzzle of the gun and tested This sample is the best representative of the quality of the iron in the body of the gun which can be obtained But as this cannot be tested for several days after the gun is cast and cooled the approximate test of the test bar serves as a guide for preparing the iron for the gun to be next cast

The machine used for testing the iron was invented by Major Wade in 1844 and has since been enlarged and improved by Major Rodman It is made to exert a force of one hundred thousand pounds which is applied or removed with great facility by the simple turning of a handcrank and it measures accurately to a single pound the resistance offered by the body under trial It is arranged for measuring the resistance of metal to tensile transverse torsional crushing and bursting forces for measuring the extension deflection compression and permanent set in either form of strain and for determining the relative hardness of metals

The specific gravity is ascertained by a hydrometer designed by Major Wade which receives specimens of any weight not exceeding two pounds It is exceedingly sensitive and gives the weight lost by the specimen in distilled water to the one hundred and forty thousandth part of the specimen weighed Duplicates of these testing machines were obtained and sent to England for use in the Woolwich arsenal by a special commission of English officers who visited the United States in 1854 for the purpose of examining the machinery used in our national armories duplicates of which also they procured for use in their public armory at Enfield

The instruments used in verifying the dimensions of cannon are numerous and well devised The Star Guage which measures the diameter of the bore the part in which the greatest accuracy is required denotes differences so minute as the one thousandth part of an inch And such is the perfection of the boring machinery and the skilfulness of the workmen now employed that the variations from the prescribed diameter of the bore rarely exceeds the one five hundredth part of an inch in any part of the bore

Government inspecting officers are present and witness all the successive operations in the manufacture of cannon from the selection of the iron for melting up to the completion of the gun all of which they note and register When the guns are finished they are carefully inspected weighed and proved and when they are received the inspector stamps upon them the official marks of reception The instrument by which they are weighed has a capacity of one hundred tons A register of all the details of the manufacture of each cannon cast and of all the tests made is kept in the foundry books also So that a minute and exact history of every gun in the public service is preserved in the ordnance offices at Washington and at the foundries

There is probably no single establishment in the United States which attracted so much of public attention during the war as the Fort Pitt Foundry It was thronged daily with visitors Many travelling strangers in passing would delay their journey a day or two in order to visit the Works Distinguished military and naval officers from England France Spain Russia Sweden Denmark Prussia Sardinia and Austria who had come from Europe to observe the operations of our armies in the field or to note the progress of the war and the manner of conducting it came from Washington city for the special purpose of examining the Works and to witness the casting of the monster cannon

From: A History of American Manufactures from 1608 to 1860, by John Leander Bishop, Philadelphia, 1868, Page 98
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