CONTENTS. 



XV 



jtrength ; Strengtk of different substances, 151. In- 

 convenience of bulk ; Friction ; Lateral adhesion ; 

 153. Uniformity of friction, 153. Usual magnitude of 

 friction; Best direction for draught; 154. Stability of 

 a wedge or nail ; 155. Resistance lo penetration ; 156. 



Lecture xiv. On architecture and 

 carpentry ; 157. 



Architecture; Form of a column; 157. Eddystone 

 lighthouse; 158. Wall; 159. Joints; Mortar; Arch; 

 160. Oblique pressure; of earth; 161. Bridge; 162. 

 Flat arch; Horizontal thrust; Piers; 163. Black- 

 friars bridge ; Dome ; 164. St. Paul's cathedral ; Pan- 

 theon; Orders of architecture; 165. Gothic architec- 

 ture ; Carpentry; Joints; 166. Scarfing ;16T. Jog- 

 gles; Tenons; Mortises; Straps; 168. Inconveni- 

 ence of transverse strains; Roofs; 169. Kirb roof ; 

 Height of a roof; 170. Wooden bridges; Centres of 

 bridges; Furniture; Parker's gates; 171. 



Lecture xv. On machinerj'; 172. 



Application of force; 172. Levers; Connected 

 rods; Hooke's joint ; Cranks; 173. Winches; Rec- 

 tification of circular motion; 174. Wlieelwork ; 

 175. Teeth of wheels ; 176. Kinds of wheels; 177. 

 Eccentric wheels ; Sun and planet wheels ; Construc- 

 tion of wheels; Weights and springs; 178. Fly 

 wheels; Air vessels; 179. 



Lecture xvi. On the union of 

 flexible fibres j 180. 



Chain ; Union by means of adhesion ; Friction of a 

 rope on a cylinder; 180. Twisting; Spinning; Rope- 

 making; 181. Materials of ropes; 182. Hemp; Flax; 

 183. Cotton; Silk; 184. Wool; Weaving; 185. 

 Crape ; Cloth ; Felts; 136. Hats; Paper; 187. 



Lecture XVII. OnTimekeepers; 18S. 



Clepsydrae; 188. Clocks; Fly clocks; 189. Ba- 

 lances; Chronometer with a revolving pendulum; 

 190. Measuremcntof minute intervals of time; Pen- 

 dulum; Balance spring; 191. Principal requisites of 

 a timekeeper; Sustaining force; 192. Equalisation of 

 the force; Intermediate spring or wheel; Scapemcnt; 

 Crank ; 193. Crutch scapement; Common, watch 

 scapement ; 194. Dead beat scapement and horizon- 

 tal watch; Friction of scapcments ; 195. See correc- 

 tions. Duplex scapement; Comma scapement; 

 Scapemcnts of Harrison, Mudge, Haley, Cumming, 

 and Nicholson; 196. Scapcments of Arnold and 

 Earnsliaw; Isoclironism of vibrations ; 197. Proper- 



ties of springs, 198. Expansion of pendulums ; Com- 

 pensations for clocks; 199. Compensations for 

 watches; 200. Resistance of the air; Striking part ; 

 201. Supports of clocks ; Mutual influence of two 

 clocks ; 202. 



Lecture xviii. On raising and re- 

 moving weights; 203. 



Counteraction of gravitation ; Levers: 203. Per- 

 rault's lever; Axis with a winch; 204. Water whim- 

 sey; Gin; Capstan; 205. Double capstan; Wheel- 

 work; String of buckets; PuUies; 206. Inclined 

 plane; Duke of Bcidgwater's canal; 207. Screws; 

 Cranes ; 208. Walking wheels ; White's crane ; 209 ; 

 Weighing cranes ; Lewis; Counterpoise for a chain ; 

 Removing weights ; Porters; 210. Distribution of 

 weight ; 211. Simple dray ; Effect of agitation ; Oily 

 substances; 212. Rollers; Friction wheels ; 2 13. Per- 

 rault's ropes; Wheels of carriages; 214. Magnitude 

 of wheels; 215. Line ofdraught; Conical wheels ; 216 ; 

 Effect of springs ; 217. Attachment of horses ; Wheel 

 ways; 218; String of baskets or carts; 219. 



Lecture xix. On modes of chang- 

 ing the forms of bodies ; 220. 



Compression; Presses; Effect of momentum; 220. 

 Printing press; Sugar mill; 221. Oil mills; Ilam- 

 meiing; Ilydrostalic press; Extension; Laminat- 

 ing machine; Glazier's vice; 222. Wire drawing; 

 Pottery; Glassblowing; Percussion; 223. Forges; 

 Goldbeating ; Coining; Stamping; Penetration; 224; 

 Pile driving engine; 225. Sling; Bow and arrow ; 22S. 

 Whip; Division; Cutting instruments; Slitting milt ; 

 227. Lathes ; Boring ; 228. Agricultural instru- 

 ments; Mining; Sawing; 229. Stonecutting; Grind- 

 ing; 230. Polishing; 231. Trituration; Powder 

 mills; Agitation; Threshing machines ; 232. Corn 

 mills; 933. Kneading; Levigating; Demolition; 

 Bolt drawer ; 234. Burning ; -Blasting ; 235. 



Lecture XX. On the history of me- 

 chanics ; 236,. 



Origin of the Grecian learning ir» Egypt; Tliale? t 

 230. Ionian school ; Italiaivschool ; Pythagoras ; 237 ; 

 Demooritus ; Invention of the arch ; 238. See correc- 

 tions. Archytas and Eudoxus; Aristotle; Foundation 

 of Alexandria; 239. Epicurus; Archimedes; 240. 

 Siege of Syracuse ; 241. Athenaeus; Ctesibius; 249. 

 Vitruvius; Middle ages; 243. British manufactures ; 

 244. Anglonorman atid Gothic architecture; 245, 



