But her significance in the history of steam-ship construction must not be under-estimated. Sir William H. White’s opinion on this point was given in his address to the Institution of Civil Engineers, in 1903, as follows; “Having recently gone again most carefully through Brunel’s notes and reports, my admiration for the remarkable grasp and foresight therein displayed has been greatly increased. In regard to the provision of ample structural strength with a minimum of weight; the increase of safety by water-tight subdivision and cellular double bottom; the design of propelling machinery and boilers, with a view to economy of coal and great endurance for long-distance steaming; the selection of forms and dimensions likely to minimise resistance and favour good behaviour at sea; and to other features of the design which need not be specified, Brunel displayed a knowledge of principles such as no other ship-designer of that time seems to have possessed, and in most of these features his intentions were realised. To him large dimensions caused no fear. ‘The use of iron,’ he remarks, ‘removes all difficulty in the construction,’ and experience of several years has proved that size in a ship is an element of speed, strength, and safety, and of greater relative economy, instead of a disadvantage, and that it is limited only by the extent of demand for freight, and by the circumstances of the ports to be frequented.” CHAPTER X THE BUILDING OF STEEL SHIPS As early as 1853 mild cast steel had been suggested for shipbuilding, and in 1855 Howell introduced it as “homogeneous metal,” but shipbuilders took little notice of the suggestion for some years. Robert Napier and Sons received orders in 1858 for some high-pressure boilers and marine machinery where lightness combined with strength was of the utmost importance, and it was proposed to use “homogeneous metal” for the one and puddled steel for the other instead of the wrought iron which was ordinarily employed. Steel as then made was very brittle and many attempts were made to remedy this defect. David Kirkaldy made a series of important experiments which lasted three and a half years and attracted the attention of the Scottish Shipbuilders’ Association. His principal service was the discovery and placing on record of the effects of oil hardening upon the properties of steel.