CONTENTS. xix 



LECTURE XXV. 



ON HYDRAULIC PRESSURE, 228. 



Pressure of fluids in motion ; Counterpressure, 228. Magnitude of the pressure 

 and impulse of fluids ; Laws of hydraulic pressure, 229. Particular case of water 

 wheels ; Oblique impulse ; Distribution of pressure, 230. Elevation and depres- 

 sion produced by the motion of a floating body ; Form of a ship ; Body moving 

 below the surface, 231. Convex surfaces ; Hydraulic pressure of the air, 232. 

 Concave surfaces ; Great effect of an increase of velocity ; Reflection of a ball or 

 stone, 233. 



LECTURE XXVI. 



ON HYDROSTATIC INSTRUMENTS, AND HYDRAULIC ARCHITECTURE, 235. 



Statics and architecture of fluids; Hydrostatic balance, 235. Hydrometer; 

 Glass globules ; Specific gravities of particular substances ; Mixtures, 236. Spirit 

 level ; Hydrostatic lamps ; Embankments, 237. Dikes ; Rivers ; Reservoirs, 238. 

 Flood gates ; Strength of sluices and flood gates, 239. Friction ; Canals ; Piers ; 

 Harbours, 240. 



LECTURE XXVII. 



ON THE REGULATION or HYDRAULIC FORCES, 241. 



Machinery of fluids ; Water pipes ; Siphons, 241. Stopcocks and valves, 242. 

 Pitot's tube ; Hydrometric fly ; Captain Hamilton's hydraulic register ; Motions 

 of the air, 243. Weight and impulse of fluids ; Raising weights by the descent of 

 water; Effect of velocity ; Overshot wheel, 244. Undershot wheel ; Mechanical 

 power of a stream, 245. Breast wheel ; Second wheel ; Oblique wheels and wind- 

 mills, 246, 247. Smoke jack ; Kite, 247. Parent's mill ; Seamanship ; Sidewind ; 

 Form and arrangement of a vessel, 248. Stability of a ship, 249. 



LECTURE XXVIII. 



ON HYDRAULIC MACHINES, 250. 



Machines for raising water ; Noria ; Bucket wheel ; Throwing wheel ; Rope 

 pump, 250. Venturi's drain ; Spiral pipes ; Screw of Archimedes ; Water screw, 

 251. Wirtz's spiral pump, 252. Centrifugal pump ; Pumps; Plunger pump, 253. 

 Forcing pump ; Mixed pump ; Pistons ; Bramah's press ; Sucking pump ; Bag 

 pump, 254. Lifting pump ; Sucking and forcing pump ; Air vessel ; Fire engine, 

 255. Roller pumps and slider pumps ; Arrangement of pipes ; Bead pump ; Cel- 

 lular pump; Chain pump, 256. Cranks; Wheels and rollers; Chinese walking 

 wheels; Inverted pump ; Hydraulic air vessels, 257. Fountain of Hero ; Atmos- 

 pheric machines, 258. Hydraulic ram, 259. 



LECTURE XXIX. 

 ON PNEUMATIC MACHINES, 259. 



Counteraction and application of pneumatic forces ; Torricellian vacuum ; Air 

 pump; Double barrel, 260. Smeaton's pump ; Experiments; Gages, 261. Pear 

 gage ; Condensers ; Diving bells ; Bellows, 262. Gasometers ; Shower bellows ; 



