The introduction of gunpowder on board ship was long subsequent to the invention of fire-arms, and was very slowly adopted by most navies. From the fact that, in the middle of the fifteenth century, a vessel of seven hundred and fifty tons burden had only a single piece of artillery, and one of fifteen hundred only eight guns, and as for a commission of four months--the usual length of a ship’s commission in the Middle Ages--each piece of artillery was only provided with five-and-twenty to thirty rounds, we see with what difficulty and how slowly the new style of weapons replaced the old one. In the ships’ inventories of 1441, side by side with _bombardes_, we find invariably figuring large cross-bows, _viretons_, darts, long lances, and complete sets of armour for the sailors. Things were not much more advanced than they were in 1379 at the celebrated naval battle of Chioggia, in which the Venetians made use, against the Genoese, of cannon constructed of pieces of metal, welded together and covered with a casing of wooden staves, bound round with stout iron bands and ropes. Some of these primitive guns exploded at their first discharge; one alone survives, and is now to be seen in the arsenal at Venice, the solitary specimen of the first attempt at projecting iron and stone shot from a tube by the ignition of saltpetre, sulphur, and charcoal. [Illustration: Fig. 91.--Prows of Galleys armed with the Spur.--From Drawings by Breugel the Elder, engraved by Fr. Huys (1550).] More than a hundred years passed away before marine artillery attained any importance; it was not till the close of the sixteenth century that Brantôme was able to put on record that he had seen in the Mediterranean a galliot armed with two hundred pieces of artillery, belonging to Cosmo I. of Medici, the Grand-Duke of Tuscany.