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KINEMATICS OF MACHINERY.

water and emptied again into the channel which carries it over the land. The Picota is still used not only in India, but also in Northern Africa, in Spain, by Belgian brickmakers, and here and there even in Germany. It is by a very similar arrangement that the Chinese worked the rope borers for driving their wonderful artesian wells. The Egyptians have for ages used an arrangement

FIG. 170.

something like the European Picota, called a Shadoof 38 ; it is, how- ever, worked by one man, and the lifting is done essentially by the counter-weight. A man standing by the bucket manages the machine. The figure on the opposite page shows a large Shadoof arrangement with three lifts.

We see a very early use of rectilinear motion in the bow and arrow, with the help in this case of an accumulator of energy, the