of the vessel.
It is an amplification and extension of the screw.
Figure 317 shows it in horizontal and transverse sections.
See screw propeller.
A form of railway in which a continuous shaft rotates on pillars erected between the lines of rail, the shaft having a spiral rib which acts as a screw upon a pedestal below the car to propel it along the track.
The invention of Archimedes when in Egypt, about 260 B. C. It consists of a hollow inclined screw, or a spiral pipe around an inclined axis; the lower end is submerged in the water and the upper end discharges.
Strabo refers to a water-raising machine of this kind, used to supply the garrison of the Memphite Babylon, on the Nile, and worked by 150 men.
It was also used as a draining pump by the Turdetani of Iberia in the time of Strabo.
This was the country of the Guadalquiver.
See screw, Archimedean.