The general interest in problems of ordnance and armor, stimulated by the Crimean War (1854-1856), was shared by Bessemer, whose ingenuity soon produced a design for a projectile which could provide its own rotation when fired from a smooth-bore gun.[13] Bessemer's failure to interest the British War Office in the idea led him to submit his design to the Emperor Napoleon III. Trials made with the encouragement of the Emperor showed the inadequacy of the cast-iron guns of the period to deal with the heavier shot; and Bessemer was presented with a new problem which, with "the open mind which derived from a limited knowledge of the metallurgy of war," he attacked with impetuosity. Within three weeks of his experiments in France, he had applied for a patent for "Improvements in the Manufacture of Iron and Steel."[14] This covered the fusion of steel with pig or cast iron and, though this must be regarded as only the first practical step toward the Bessemer process,[15] it was his experiments with the furnace which provided Bessemer with the idea for his later developments. [13] British patent 2489, November 24, 1854. [14] Bessemer, _op. cit._ (footnote 7), p. 137 He received British patent 66, dated January 10, 1855. [15] See James W. Dredge, "Henry Bessemer 1813-1898," _Transactions of the American Society of Mechanical Engineers_, 1898, vol. 19, p. 911. These were described in his patent dated October 17, 1855 (British patent 2321). This patent is significant to the present study because his application for an American patent, based on similar specifications, led to the interference of William Kelly and to the subsequent denial of the American patent.[16] In British patent 2321 Bessemer proposed to convert his steel in crucibles, arranged in a suitable furnace and each having a vertical tuyere, through which air under pressure was forced through the molten metal. As Dredge[17] points out, Bessemer's association of the air blast with the increase in the temperature of the metal "showed his appreciation of the end in view, and the general way of attaining it, though his mechanical details were still crude and imperfect." [16] See U.S. Patent Office, Decision of Commissioner of Patents, dated April 13, 1857, in Kelly vs. Bessemer Interference. This is further discussed below (p. 42). [17] Dredge, _op. cit._ (footnote 15), p. 912. [Illustration: Figure 1.--BESSEMER'S DESIGN FOR A CONVERTER, AS SHOWN IN U.S. PATENT 16082. This patent, dated November 11, 1856, corresponds with British patent 356, dated February 12, 1856. The more familiar design of converter appeared first in British patent 578, March 1, 1860. The contrast with Kelly's schematic drawing in Fig. 2 (p. 42) is noticeable.]