KEY AND INDEX 



Walking Beam. A beam, or bar, used on a certain type of 

 steam engine to convert the reciprocal motion of the piston into 

 rotary motion. At the present time the walking beam is little 

 used except on side-wheel river steamers. See "Final Improve- 

 ments and Missed Opportunities," Vol. VI, p. 102. 



Water. A universally diffused liquid, with the formula H,O 

 (two atoms of hydrogen and one of oxygen). The chemical com- 

 position of water was discovered in 1781 by Henry Cavendish. 

 James Watt is also credited with priority of this discovery, but 

 Cavendish's claim is fully established. See Vol. IV, p. 14. 



Water Engines. See "The Work of Air and Water," Vol. 

 VI, p. 70. 



Water-frame. The name given Arkwright's spinning-frame. 

 See Vol. IX, p. 25. 



Watermills. Mills driven by water-power appear to have 

 been introduced in the time of Mithridates, Julius Caesar, and 

 Cicero. When the Goths besieged Rome in 536 and cut off the 

 water supply for running the mills the Romans constructed 

 floating mills on the Tiber. Mills driven by the tide existed in 

 Venice as early as 1078. See "The Work of Air and Water," 

 Vol. VI, p. 70. 



Water-motor. Any water-wheel or turbine run by water. In 

 1838 Lord Armstrong had a water-motor constructed along lines 

 similar to the modern steam turbine engine. Its efficiency was 

 ninety-five per cent, and it developed five horse-power at thirty 

 revolutions per minute. See Vol. VI, p. 70. 



Water-wheels. See "Watermills" of the present index. 



Weaving. The art of producing textile fabrics, such as cloth, 

 network, lace, etc., from a combination of threads on a loom. 

 Hand weaving was known in prehistoric times, but the modern 

 art of weaving dates from John Kay's invention of the flying 

 shuttle (Vol. IX, p. 42), in 1738, and Dr. Cartwright's invention 

 of the power loom about 1784 (Vol. IX, p. 43). See "An Indus- 

 trial Revolution," Vol. IX, p. 5; and "The Manufacture of Tex- 

 tiles," Vol. IX, p. 38. 



Wedge. A special application of the inclined plane, con- 

 sisting of a very acute-angled triangular prism of hard material 

 driven between objects to separate them. The screw is also an 

 example of the use of the inclined plane, but is used for an en- 

 tirely different purpose from the wedge, the object of its use 

 being to hold objects together. 



Wheel. A circular disk or frame turning on an axis. The 



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