Had the invention been patented, it would have become public property in fourteen years from the date of the patent, after which period the public would have been able to buy bronze powder at its present [_i.e._, _ca._ 1890] market price, viz. from two shillings and three pence to two shillings and nine pence per pound. But this important secret was kept for about thirty-five years and the public had to pay excessively high prices for twenty-one years longer than they would have done had the invention become public property in fourteen years, as it would have been if patented. Even this does not represent all the disadvantages resulting from secret manufacture. While every detail of production was a profound secret, there were no improvements made by the outside public in any one of the machines employed during the whole thirty-five years; whereas during the fourteen years, if the invention had been patented, there would, in all probability have been many improved machines invented and many novel features applied to totally different manufactures. [9] _Ibid._, p. 82. [10] _Ibid._, p. 83. While these words, to some extent, were the rationalizations of an old man, Bessemer's career showed that his philosophy had a practical foundation; and, if this was indeed his belief, the episode explains in large measure Bessemer's later insistence on the legal niceties of the patent procedure. The effect of this will be seen. Bessemer's intervention in the field of iron and steel was preceded by a period of experiments in the manufacture of glass. Here Bessemer claims to have made glass for the first time in the open hearth of a reverberatory furnace.[11] His work in glass manufacture at least gave him considerable experience in the problems of fusion under high temperatures and provided some support for his later claim that in applying the reverberatory furnace to the manufacture of malleable iron as described in his first patent of January 1855, he had in some manner anticipated the work of C. W. Siemens and Emil Martin.[12] [11] _Ibid._, p. 108 ff. [12] _Ibid._, p. 141. Bessemer's assertion that he had approached "within measurable distance" of anticipating the Siemens-Martin process, made in a paper presented at a meeting of the American Society of Mechanical Engineers (_Transactions of the American Society of Mechanical Engineers_, 1897, vol. 28, p. 459), evoked strong criticism of Bessemer's lack of generosity (_ibid._, p. 482). One commentator, friendly to Bessemer, put it that "Bessemer's relation to the open-hearth process was very much like Kelly's to the Bessemer process.... Although he was measurably near to the open-hearth process, he did not follow it up and make it a commercial success...." (_ibid._, p. 491).