Page:The Kinematics of Machinery.djvu/241

 THE LEVER, 219

apparently primitive. The strands run from 'the two-footed frame a, (which is kept from moving forwards by a strong stay rope) to the place where the twisting is to be done. The European ropemaker uses for that purpose a wooden cone fitted with guiding grooves so formed as to give the strands the required twist, the part of the rope which has been finished being caused to rotate continuously about its own axis. The Egyptian ropemaker, however, uses his hand instead of the cone ; he guides the strands most dexterously with his fingers, always walking slowly towards the frame a. The four spindles to which the strands are attached, must, at the same time, in order to maintain the required twist, be continuously turned, like the rope, about their axes. This is done by the help of the endless cord c carried twice round them, and pulled continually by two men. At d this rope passes through a ring, which is so made as to offer a certain resistance to its motion, so as to keep its tension sufficiently constant.

The hand spinning-wheel is in such widely extended use among the Indians, Chinese, Japanese and the peoples of the Malayan Archipelago that a considerable antiquity must be ascribed to it It was not unknown, either, to the Komans. Among us, on the other hand, it appears that spinning was not done by the help of the wheel before the middle ages by the foot-worked wheel not before the sixteenth century; the latter somewhat altered the method used, but the greater portion of the work was still left for the hand of the worker.

The working of the spun threads into a web by some kind of loom was done as early as the time of the lake-villages. The apparatus used was not, however, a machine in our sense. Ac- cording to the remarkable reconstruction of it by Herr Paur in Zurich it is more like a pillow lace apparatus, possessing no more than the germs of specially machinal characteristics.

The Picota or Kuppilai of India, shown in Fig. 170, is a very old machine, although scarcely one that reaches back to pre-historic times. Here we find a lever used. A rod carrying a water-bucket is fixed to one end of a rocking-pole or beam, and a sort of counter- balance to the other. The beam rests in forked bearings, where it is further secured by cords. Men stand upon the beam, and by stepping backwards and forwards upon it cause it to swing up and down, so that the bucket can be dipped by a third man into the