INDEX. 463 



Valves of a pump, 140. 



Vitreous humour of the eye described, 240 



Vision, its nature, 238. 



Watt, Mr. James, improved steam-engine by, 166. 



Water-wheels, over and undershot, 107. 



Water, compressibility of, 113. 



Water-mill, 79. 



Wagoni., tje best mode of constructing, 99. 



Wedge, 69. 



\\inds, their nature explained. 



Wheel and axle, 60. 



Whirling-table described, 33. 



Worcester, Marquis of, his fleam-engine, 163- 



