There was no sudden change from iron to steel in the building of warships. Steel at first was very expensive, and by no means the perfect article that we know at the present day, besides which the supply was very restricted, and the Admiralty by using it in conjunction with iron was able to ascertain the extent to which it might ultimately be adopted. Thus, in one ship, steel was tried for the keel, in another for the protective deck, in another for facing armour, in another for the frames, and so on. The two screw propeller shafts of the _Inflexible_, for instance, were made of Whitworth compressed steel. They were 288 feet in length and weighed 63 tons. Had they been of wrought iron they would have weighed 97 tons. One of the earliest steel warships ever built, and certainly one of the smallest, was the Dutch gunboat _Handig Vlug_, launched on the Thames in 1864. Commenting on this little gunboat, the _Times_ said: “The general term ‘gunboat’ conveys to our minds the image of a vessel built of ‘sappy timbers’ and rotten planking, carrying two heavy shell guns on their low unprotected upper deck, fitted with 60 h.p. (nominal) engines, and averaging no more than eight knots under the most favourable circumstances, a class of vessel that has figured for almost fabulous sums in our annual navy estimates for ‘repairs,’ etc., but, nevertheless, a class of craft that has left imperishable marks of its usefulness and power in many parts of the world, and more especially on the rivers and seaboard of India and China.”