A further acquisition was the art of braiding and plaiting, the joining together of flexible materials in such a way that they held together by force of friction alone. Thus coherent, durable fabrics may be produced, and by joining together small parts into an aggregate it is also possible to give a definite form to the whole and to adapt it to various uses. The quality of adaptability is especially developed in the products of plaiting, but the quality of imperviousness is lacking. Wickerwork was used not only in the form of baskets, but also in other shapes, as means for protection and shelter, as material for sails, as well as for tying and binding. The art of weaving arises from plaiting, and along with it come methods for spinning thread. It thus becomes possible to make an immense number of different useful articles out of shapeless vegetable material. Fibres are rendered more durable by being bound together, and textures formed from threads are adapted to the most various uses of life. This has an influence on the development of weapons also: bow-strings, slings, and lassos presuppose a rudimentary knowledge, at least, of the textile arts; and as knowledge increases, so are the products improved in turn. [Illustration: MAN’S METAL DRESS: THE DEVELOPMENT OF ARMOUR FROM ANCIENT TO MEDIÆVAL TIMES The way in which man has protected himself against his foes in battle, and the gradual progress and decline of such methods, is shown in these pictures. The first is from the monuments of Nineveh, and shows the earliest form of chain mail. In the second we see the armour of the Roman legionary, while the third shows the heavy accoutrement of a mediæval warrior. A helmet of the same period is also shown. ] Means for conveyance are also invented, that difficulties arising from distance may be overcome. At first men carry burdens upon their backs, heads, or shoulders, or in the hand, placing whatever they wish to transport in a utensil--a basket or a piece of cloth--thus producing a coherent whole; later, in order to render conveyance still more convenient, handles are invented. Objects are dragged along the ground, and from an effort to save them from injury the idea of sledges develops. Things that are round enough are rolled to their destinations; this leads to the invention of rollers and wheels, materials of required form being brought into combination with rudimentary agents of circular motion, and thus, through a rotary, a horizontal movement is obtained; and so the force of gravity is made use of, consistency of motion procured, and the hindering effect of friction overcome to the greatest possible degree. Means for carrying inanimate objects once invented, it is not long before they are put to use for the conveyance of man himself; thus methods for the transportation of human beings are discovered in the same manner as the means for the carriage of goods. [Sidenote: Man’s First Boats]