There were “in full operation, a most extensive series of well-contrived apparatus, adapted to the manufacture of artillery guns, of varying magnitude and widely divergent calibre, from the small and light piece of ordnance suited to the exigencies of mountain warfare, and discharging a ball of 4 pounds weight up to the huge 100 pounder suited for the deck of an ironclad Warrior or Black Prince, or fitted to defend, or to assail the most formidable of defensive works. Some of these great guns were almost in the earliest initiatory state of manufacture, others far advanced towards completion, while others again were perfected and ready for delivery. Nearly all these powerful implements of war and destruction were constructed on what is known as the Blakely principle, that is, on the principle invented by Captain Blakely, which is recommended as combining great strength of resistance to explosive action, immense power of range, and economy as regards first cost. The principle upon which this formidable implement is constructed has been frequently described, yet as it is, like most other inventions of merit, exceedingly simple, it may not be out of place here a remark or two descriptive of the process.”

“In the first instance the size and consequent proportion of the gun having been determined on, a core or heart-piece, forming a complete gun, is cast solid on end, the breech being cast undermost, and the gun of considerably greater length than is wanted, to insure perfect soundness and solidity in the cast. The superfluous length is then cut off from the muzzle end, and the gun bored out to the requisite calibre. Captain Blakely’s principle of gun construction, however, includes the manufacture of the interior, or central portion, of steel or of wrought-iron, although he prefers cast to wrought iron, as being in his estimation, in every way better. So far this differs little from the old process of making cast-iron cannon; but after the manufacture has been accomplished thus far, the process invented by Captain Blakely, which we understand, has been secured by a patent, comes into operation. This consists of hooping the iron or steel gun with a series of steel rings, made of the first class and most tenacious steel. These being bored to the requisite diameters, and heated, are placed on the gun at the breech end, extending from the trunnions backwards, and completely enclosing the breech, and while at a moderately high temperature , their lateral joinings are securely placed together, and as the steel casing applied in the manner stated, contracts by cooling, it forms an inseparable and hard binding of finely prepared steel, varying in thickness from half-an-inch to three or four, or any number of inches, according to the size of the gun and the requirements of service to which it is to be applied. Besides the steel rings referred to in guns of large calibre, Captain Blakely also introduces a strong binding jacket of cast steel, over which he places his binding steel rings, the whole forming a very strong support in resistance to the expansive force exercised by the explosion of the charge of powder. When the process of cooling, and thus securely fastening the formidable steel binding of the cannon has been completed, the exterior surface is then trimmed and fashioned in the ordinary way, on a turning-lathe suited in power to the magnitude of the gun.”

“From the preceding brief outline it will be seen that the principle and also the manipulation of this style of gun are founded on strictly scientific principles, and on qualities well-known as pertaining to the materials used. Great care is, of course, requisite to have each casing and ring of the precise diameter suited to bring its strength to bear, and this being ascertained by abstruse calculation and numerous experiments, forms the only secret of the manufacture. Guns made on this principle are said to possess numerous advantages over those which are simple cast of iron, and also over those which are made altogether of wrought-iron. Their superiority over the former consisting chiefly in their greater strength, and consequently in their greater range, as compared with the latter; greater cheapness also constitutes an important advantage; whilst in the case of the Blakely gun, the trunnions being cast in the original metal of which the heart-piece or jacket is formed, they constitute integral parts of the gun, and require no troublesome process of hooping on, and are not liable to be detached from the gun while it is use.”

“The exterior of the gun having been finished as suggested, and the boring having also been completed as already stated, the implement may now be considered complete, unless it be intended to have it made on the improved principle of rifled ordnance, in which case the process of rifling has yet to be gone through; but this thanks to the inventions of modern science, and the ingenious apparatus employed by Messrs Fawcett, Preston & Co., is not an operation of great difficulty or tediousness.”

“Before quitting, the subject of the manufacture of these guns, it is right to state that Captain Blakely’s great object being to ensure strength at the breech, he has designed the exterior aspect with an especial eye to ensure that, and he adheres, although not exclusively, to the principle of muzzle-loading.”

6 inch Blakely gun, pattern 1866

A hammered cast-steel tube, with a cast-steel sleeve and trunnion ring

97 inches length overall, 10.87 inch diameter of tube, 18 inch maximum diameter

Construction in 1866

Five years later, Engineering magazine, on January 12, 1866, was to write:  

“The Blakely Gun - A little more than ten years ago we were in the thick of the Russian war. The science of ordnance had been neglected during a long period of peace, a period when there were many who, no doubt, sincerely believed the world was on the eve of the millennium. But war soon taught us that even if our guns were as good as those of our enemies, we needed others very much better than theirs. The occasion suggests the invention, although there may be those who prefer the old and wise saw of ‘necessity is the mother,’ &c.”  

“Captain Blakely and Mr Mallet saw what was required, but Mr Mallet did not propose an altogether practicable gun, while Captain Blakely did. On the 27th of February, 1855, before the then Mr William G Armstrong had given to the public, or even the Privy Council, his own ideas of guns, Captain Blakely secured a patent for the mode of making cannon with steel or cast-iron inner tubes, strengthened by wrought iron or steel jackets shrunk over them with a considerable  initial tension. This idea of initial tension was not, perhaps, clearly expressed in the original patent, but Captain Blakely secured it by a disclaimer and memorandum of alteration, early in 1859. Mr Mallet had tried the principle in the 36 inch mortar, first fired with a shell, weighing one ton and a quarter, October 19th, 1857, but the monster mortar was not made as we should now make such a piece of ordnance, even if we were working upon the principle then laid down.”

36 inch Mallet’s Mortar 1856

The largest calibre ordnance in the world, ever. Its bombs weighed over one ton

The barrel was made in horizontal segments for transportation

“We can understand in a little time exactly what is the principle of the Blakely gun.”

“Captain Blakely appears to have reasoned in this way: ‘In exploding powder within the chamber of a gun, the first effect is that of percussion, and steel will withstand this much better than wrought iron. Therefore, I will make my inner tube of steel. But the internal surfaces of the chamber, being strained, will stretch, whereas the metal outside and beyond them will be extended in a less and less degree according to a principle some years ago demonstrated  by Professor Barlow, who showed, that, beyond a certain thickness, no additional metal would give more strength to a hydraulic press cylinder.’  If we can in imagination follow Captain Blakely’s reasoning from what he has since done, we may suppose that he summed up in words much like these: “I will first place the material immediately surrounding the bore, in a state of compression, by shrinking wrought-iron tubes or rings upon the outside. Then, when the powder explodes, the outer tubes or rings will be made to do their work, and this inner tube will, in the first extension due to explosion, come merely to a state of repose, afterwards extending by tension. Thus a great deal of the force of the powder will be expended before the metal of the inner tube is really brought into tension.’ We are here putting words of our own into the mouth of another, but Captain Blakely’s specification, and his later practice as an ordnance engineer, show exactly what his governing ideas must have been. In his principle of throwing work upon the outer metal of the gun, beyond what it ever before has borne, he has been imitated by Sir William Armstrong, by Parrott, and by Captain Brooke of the late Confederate Army [Navy], who fabricated many guns - essentially upon Captain Blakely’s principle - at the Tredegar Works, Richmond, Virginia.  And this principle has been adopted by all the great military powers of the world.”

“The earlier Blakely guns were of cast iron, hooped with wrought-iron jackets.  The Parrott guns, made by Mr R P Parrott, of West Point Foundry, in America, were of this construction; but they burst to such an extent, when employed as naval guns, as to disqualify them for service. At the attack on Fort Fisher, more men were killed by the bursting of the Parrott guns than were killed by their fire. Captain Blakely some considerable time ago abandoned both cast-iron bores and wrought-iron jackets, substituting steel for both. All Blakely cannon are now, we believe, made of cast steel, cast by Messrs Thomas Firth and Sons, and Messrs Naylor, Vickers, and Co. of Sheffield, although the steel of other makers may be used. Very large guns have been made, and one of 15 inch calibre is now in course of construction at the Blakely Ordnance Works, Bear Lane, Southwark, the new works at East Greenwich not being yet completed. The 15 inch gun, of which we will soon give an engraving, will weigh 21 tons. We cannot say to where this gun will be shipped when completed, but when we recollect that, on the occasion of General Todleben’s visit to England last year, the Blakely Company received on order to the extent of nearly £1,000,000 for guns for Kronstadt and other Russian fortresses, it is not unlikely that the great gun may yet find a home in some fortification on the banks of the Neva.”

“General Ripley, who commanded the inner defences of Charleston, during the memorable siege of that town, lately informed us that he had, among other Blakely guns, one of 12¾ inch bore, the inner tube of cast iron and the jackets of steel.  He fired it about 100 times in all, the service charges being 45 pounds of powder, afterwards increased to 60 pounds, and with a cylindrical shot of 600 pounds weight.  The elevation did not exceed 5˚. After the close of the war, on his way to New York, the General learned that the gun had been purposely burst; but no less than 120 pounds of powder and 1,300 pounds of iron were required to effect this.”

“The present Woolwich guns, with steel inner tubes and shrunk-on outer casings, are made generally in accordance with the specifications of Captain Blakely, although no credit is given; and, it is as well to say it, no royalty is paid to the patentee.”

Making cylinders out of spiral turned wrought-iron or steel bars, 1862,

before being forged by steam hammers into the hoops to surround gun barrels.

Blakely used a similar process for the sleeves and hoops on his pieces