This article first appeared in Practical Engineering 1940 Vol1 No21. The article contains within it information that is therefore valid as of 1940. This article discusses matters of historical significance to the development of Engineering, Industry and Manufacturing.
It has been said that, next to the invention of the steam engine, Sir Henry Bessemer's introduction of mild steel about the middle of the last century contributed more to the progress of engineering and mechanical science than any other single discovery. Previous to Bessemer's first introduction of mild steel in 1856, the majority of heavy machinery had been made of iron—wrought iron and cast iron.
It is true that almost a century before Bessemer's epoch-making invention, steel had been made in one form or another. We are told, for instance, that in the eighteenth century, certain types of steel came from India, and that this material sold for as much as five guineas a pound. Huntsman, a Doncaster clockmaker, in 1740 succeeded in producing small quantities of an impure steel for spring making and other purposes, but apart from such usages there was no demand for steel in the engineering world before the advent of Bessemer.
Henry Bessemer was born in the little Hertfordshire village of Charlton, on January 19th, 1813. He was the youngest son of one Anthony Bessemer, an individual who in many ways was himself something of a mechanical genius. The parent Bessemer, although London born, had spent a good deal of his lifetime on the Continent and had distinguished himself as an inventor. Settling in Charlton, however, Anthony Bessemer sought to live a retired life, and it was during this period of his existence that the future Sir Henry Bessemer was born. Henry Bessemer received a good-education and from his earliest years showed a great aptitude for things mechanical.
When he was seventeen years of age the entire Bessemer family removed to London, and young Henry Bessemer, who had picked up the art of making castings in metal, began to commercialise his hobby. Very soon he was making art castings for exhibitions, and at the age of twenty he devised methods of reproducing such castings mechanically.
It was at this period of his life that Henry Bessemer made the invention in reward for which he was knighted years afterwards. This invention comprised a method of mechanically perforating Government stamps in order to prevent their misuse. The invention was a simple one and it was adopted by the Government. It appears that Bessemer received no payment for his invention. He had forgone the patenting of it, relying upon the official promises of an adequate monetary reward. As a result of this early disappointment, Bessemer became a shrewd and hard-headed business man, and never again did he allow himself to be "caught" in matters respecting his subsequent inventions.
It was about this time that Bessemer invented a bronzing powder for the coloration and protection of metals. With the aid of his brother-in-law, he commenced the manufacture of this material. So successful was the bronzing powder that its manufacture was carried on for nearly 40 years.
In addition to devising this powder, Bessemer, before he hit upon his steel-making invention, brought out many ingenious processes and devices. Among these was a machine for grinding and polishing plate glass, and also several processes for purifying sugar and for mixing oils, paints, and other materials.
In 1854 - the year of the Crimean War - Bessemer invented a new type of rotating shell or projectile which he considered to be superior to all existing forms of shells. He submitted his projectile to the British War Office and to the authorities of the arsenal at Woolwich, but from both quarters he met with a blank and uncompromising refusal to have anything to do with the invention.
Bessemer, therefore, decided to look for an outlet for his invention abroad. He met with great encouragement from the Emperor Napoleon III, who not only granted the inventor many facilities for demonstrating his new projectile but also placed funds at his disposal to defray expenses.
Bessemer's demonstrations of his projectile were eminently successful, but one of the French military experts, a Commandant Minnie, remarked when giving his judgment: "The projectiles rotate properly, but if Mr. Bessemer cannot get a stronger metal for his guns, such heavy projectiles will be of little use."
Bessemer took these words deeply to heart. A new metal for guns. At that time the heaviest cannons were constructed throughout of cast iron—and how could iron be made stronger? Convinced of the truth inherent in Commandant Minnie's judgment, Bessemer gave up the whole of his energies to acquiring knowledge and information on the subject of metallurgy in general and of iron manufacture in particular.
Up to the year 1856, almost all the iron used in the world's industry was either cast or wrought. Cast iron could be obtained in large amounts and produced in intricate designs and mouldings. Wrought iron, on the other hand, although stronger and more enduring, was produced only with comparative difficulty, whilst steel, apart from its very restricted uses, was almost unknown in industry.
Having acquired as much knowledge as he could on the subject of iron-making, Bessemer settled again in London, and purchasing an old factory at St. Pancras gave himself over to the task of producing steel in commercial quantities.
Of the many semi large-scale experiments which Bessemer devised at this particular juncture we have not the space to relate. Eventually, however, the indefatigable inventor discovered that by melting cast iron in a special type of furnace and then by blowing a current of compressed air through it, the impurities were, to a large extent, burnt out of the molten metal which, ultimately, was almost completely converted into soft, malleable "wrought" iron. If the air-blowing operations were stopped before all the carbon was burnt out of the molten iron, a product was obtained which showed properties intermediate between those of cast and of wrought iron. This, of course, was steel, and before long the Bessemer steel came to be known as "mild steel."
Cast iron, as the reader no doubt will be aware, contains many impurities, chief among which is carbon. When the carbon is burnt out of the iron and most of the other impurities are removed, the iron is obtained in an almost pure condition, in which state it is known as wrought iron. If, however, a fixed percentage of carbon is allowed to remain in the metal, the product is then known as steel.
Bessemer was quick to commercialise his process of steel manufacture. By means of it, the molten iron was run into a barrel-shaped vessel which he called a converter, and in which it was subjected to the action of an air blast. Large quantities of steel, Bessemer showed, could be manufactured by this process and, after patenting it, he profited to the extent of some £27,000 in respect of payment for licences to work the process.
Bessemer's success, however, was short-lived. The licensees of the process found, after repeated attempts, that, even when they followed Bessemer's instructions to the letter, the steel-making process simply did not work. At this stage the circumstances in which Bessemer found himself were not enviable. He was regarded as a trickster and a charlatan, as a mere opportunist and a selfish money-maker.
Bessemer himself, however, was quite unable to explain the failure of his process. In his attempts to solve the perplexing problem he enlisted the aid of eminent chemists to make analyses of the materials involved in the failure of his process. Eventually, these investigations showed plainly that the failure of his process in the hands of the iron manufacturers was due to the fact that the latter were all using as raw material iron which contained relatively large amounts of phosphorus. Bessemer's "converting" process did not remove the phosphorus from iron.
Bessemer had been successful with his process simply because, in his trials, he had happened to use iron which was practically free from phosphorus.
Nearly two years were spent by Bessemer in costly and laborious experiments in the removal of phosphorus from pig iron before it was subjected to his "converting" or steel-making process, but all these experiments ended in failure. Ultimately, therefore, he had to rely for the success of his process upon supplies of foreign pig iron which were very low in phosphorus content.
It now remained for Bessemer to arrange for an ample supply of Swedish iron ore, low in phosphorous content, to be imported into this country and to be placed at the disposal of the iron manufacturers. This he did, but unfortunately the iron manufacturers, frightened by the memories of their former losses and disappointments, would have nothing more to do with Bessemer or his process. Instead, they continued to pin their faith to cast iron as the strongest form of iron which could be produced commercially in large quantities.
The Bessemer Company itself, however, forged ahead with its production of mild steel by its own process. Gradually, it became able to introduce its steel into commercial undertakings. For instance, in 1861 rails made from Bessemer steel were laid down at Crewe railway station, and at the International Exhibition of 1862 the Bessemer Company exhibited steel forgings comprising gun barrels, cylinders, shafts, and so forth, all of which demonstrated the great and enduring value of the new Bessemer steel.
After the advantages of the new steel had been proved, the demand for licences to manufacture it began to grow once again. Bessemer, it has been estimated, netted more than a million pounds in royalties from his steel patents alone and, before long, he found himself one of the most talked-of men in the industrial world.
The manufacture of Bessemer steel soon spread to other countries. Bessemer steel plates gradually began to be employed by shipbuilders and, after a few more years had elapsed, the all-wood sailing vessel had become obsolete.?
It is curious to note that despite the universal success of Bessemer steel, the authorities at Woolwich Arsenal remained for a long time conservative and refused to have anything to do with it, placing their faith, instead, in cast iron as a metal for ordnance construction.
Bessemer, at the height of his success, received the honour of knighthood, as a reward, it was mentioned, for his early invention of a means of making Revenue stamps "forgery-proof."
The subject of astronomy also occupied Bessemer's attentions. He had constructed for his own use a number of powerful telescopes, with which he made observations, and at the time of his death, which took place on March 15th, 1898, the famous inventor and steel-maker was busily occupied with plans for the construction of a giant telescope of his own special design.