Although the introduction of steel as a material for shipbuilding dates at least as far back as 1860, its use has been but partial or occasional until within very recent times. The uncertainty as to quality, the frequent great disparity between pieces cut from the same plate, and the special care needed in the manipulation, prevented its general adoption. With the highly-improved “mild steel,” however, first manufactured in France, and applied to shipbuilding purposes there about nine years ago, and subsequently introduced into this country, began the more extended adoption of steel, which every day, or with every accession to experience, is displacing iron. The facts relating to the introduction into this country of mild steel for shipbuilding purposes, may be briefly recounted. In the latter end of 1874, Admiral Sir W. Houston Stewart, Controller of the British Navy, and Mr N. Barnaby, Director of Naval Construction, availed themselves of the opportunity to observe and study the use of steel in the French dockyards of Lorient and Brest, where three first-class armour-plated vessels were then being built of steel throughout, supplied from the works at Creusot and Terrenoire. Mr Barnaby, at the meetings of the Institution of Naval Architects in March following, gave an account of his observations during this visit, and pointed out clearly and precisely to the steel-makers of Great Britain all the indispensable conditions which would have to be met and satisfied by steel for shipbuilding, so that it could be used with confidence in the construction of the largest vessels. Before the end of 1875, the Landore-Siemens Company was enabled to fulfil these conditions, and the Admiralty contracted with them to supply the plates and angles necessary for the construction of two cruisers of high speed—the _Iris_ and the _Mercury_. The material involved in this contract was steel obtained by the Siemens-Martin process. Shortly after this the Bolton Steel Company was in its turn able to produce by the Bessemer process plates and angles, satisfying all the requisite conditions. The Steel Company of Scotland, Butterly Company, and other important works, also entered into the same business, and operations are still going on in various parts of the country connected with the formation of new works, and the perfecting of other processes.