But in all these objects there is a defect; so it is concluded that these specimens were refuse thrown aside in the process of manufacture. As at Cissbury, very few polished flints are found, so we may conclude the majority of weapons were carried elsewhere for completion. But some weapons were completed here. In the neighborhood have been found the stones used as polishers. This cut shows us one used in polishing the axes. The workmen would take one of the rough-hewn instruments, and, rubbing it back and forth on such a stone as this, gradually produced a smooth surface and a sharpened edge.28 Polishing Stone. We have suggested that our civilization owes a great deal to flint. If we will consider the surroundings of their manufacturing sites, we will see the force of this remark. It must have taxed to the utmost the powers of these primitive men to sink the shafts and run the galleries to secure a supply of this valuable stone. In short, they had to invent the art of quarrying and working mines. This would lead to the division of labor, for while one body of men would become experts as miners, others would become skillful in chipping out the implements, and still others would do the finishing and polishing. A system of barter or trade would also arise, for the workmen at the mines and factories would have to depend on others for food and clothing, and in payment for the same would furnish them implements. As localities where flint could be obtained in suitable quantities are but few, we can see how trade between widely scattered tribes would arise. This kind of traffic is shown to have extended over wide distances in Neolithic times. For instance, there was been found scattered over Europe axes made of varieties of stone known as nephrite and jade. They were highly valued by primitive tribes, being very hard and of a beautiful green color. They are thought to have been employed in the observance of superstitious rites. But quarries of these varieties of stone do not occur in Europe. An immense amount of labor has been expended in finding their native home. This is now known to be in Asia.29 Manufactured in Asia, axes of these materials may have drifted into Europe and finally arrived in England. Neolithic Boat-making.