Page:The Kinematics of Machinery.djvu/230

 208 KINEMATICS OF MACHINERY.

in the temples of Thibetan and Japanese Buddhists. These are in part windmills, in part undershot water-wheels ; their use in worship Geiger traces with great skill to the awe with which the continuous rotary motion was regarded, but does not go further into the consideration of the interesting question before us.

The potter's wheel, still unknown to the lake-villagers, is not apparently of an earlier date than these water-wheels ; it represents, however, an earlier employment of more or less continuous rotation ; it is very possible that before the employment of a rotating mass to carry on the motion once it was started, the potter may have had an assistant to keep the wheel continually in motion by whirling its spindle with his hands.

The question as to the origin of the carriage and carriage wheels is very interesting to us, for the latter as kinematic contrivances permit important conclusions to be drawn as to the previous exist- ence of other machinal arrangements. Among the Greeks, Egyp- tians and inhabitants of Western Asia we find two-wheeled vehicles very early in use. 26 Their introduction travelled apparently from East to West; for a long time they served both Greeks and Egyptians as the chief, indeed almost the only, means of horse transport, whether in war, commerce, or public processions. Eiding came late into use among these nations, brought from the countries East and North of them. The Homeric heroes do not ride, but drive in battle ; indeed riding men were in those days thought of as wild uncivilised barbarians, as the myth of the Centaur shows us. The bas-reliefs of the Assyrians, on the other hand, indicate that among them both riding and driving were known. The chariot was in that time an invaluable instrument of warfare, the possession of which in preponderating numbers as with us of cannon gave an army an enormous advantage over its antagonists. We read for instance in the Bible (Judges i. 19) that the Israelites on their entry into Palestine felt greatly their want of chariots. Although Judah took possession of the high lands he was not able to drive out the dwellers in the valleys, "for they had chariots of iron"; see also Deborah's Song (Judges iv.). The want does not appear to have been permanently supplied until long afterwards, first perhaps in the battles of David, in one of which he is said to have taken 700 chariots from the Syrians (2 Sam. x. 18). 27