XIV 



COKTENTS. 



^7. Pullies; 68. Blocks; Smeaton's pulUes; 69. 

 Oblique ropes ; Inclined plane ; 70. Wedges; Props, or 

 shores; 71. Screws; Nuts; Hunter's screw ; 72. De- 

 termination of mechanical power from virtual veloci- 

 ties ; 73, 74. 



Lecture vlii. On collision ; 75. 



Motions of various bodies acting reciprocally; 

 Elastic bodies; 75. Nature of repulsion; Experiment on 

 nn ivory ball ; Apparatus for experiments on collision; 

 76. Inelastic bodies; Energy; 78. Measure of force ; 

 llelation of labour to energy; 79. Preservation of 

 energy; or of ascending force; Effect of a blow; 30. 

 Rotation; Billiards; Reflection; 81,82. 



Lecture ix. On the motions of con- 

 nected bodies ; 83, 



Rotatory power ; 83. Consideration of the square of 

 the velocity ; Smeaton's apparatus ; Centre of gyration; 

 84. Centre of percussion and of oscillation ; Free ro- 

 tation ; 85. See corrections. Motion of a stick broken 

 by a blow; 86. Preponderance; Greatest effect of 

 machines ; Experiments ; 87, 88. Cautions with regard 

 to the construction of machines ; 89. Comparison of 

 animal with inanimate force; 90. Regulation of force ; 

 Small momentum of machines; Impossibility of a 

 perpetual motion ; 91,92. 



Lecture x. On drawing, writing, 

 and measuring ; 93. 



Subjects preliminary to the consideration of prac- 

 tical mechanics; Instrumental geometry; Statics; Pas- 

 sive strength ; Friction; 93. Drawing; Outline; Pen; 

 Pencil; Chalks; 94. Crayons; Indian ink; Water 

 colours; Body colours; 95. Miniatures; Distemper; 

 Fresco; Oil; 96. Encaustic paintings; Enamel; Mo- 

 saic work; Writing; 97. Materials for writing; 98. 

 Pens; Inks; Use of coloured inks for denoting num- 

 bers; 99. Polygraph; Telegraph; Geometrical in- 

 struments; Rulers; 100. Compasses; Flexible rul- 

 ers; 101. Squares; Triangular compas.ses; Parallel 

 rulers; Marquois's scales; 102. Pantograph; Pro- 

 portional compasses; 103. Sector; Measurement of 

 angles; 104. Theodolites ; Quadrants; Dividing engine; 

 Vernier; Levelling; 105. Sines of angles; 106. Gun- 

 ter's scale ; Nicholson's circle ; Dendrometer; Arith- 

 metical machines; Standard measures; Quotation 

 from Laplace; 107. New measures; Decimal divi- 



sions; 108. Length of the pendulum, Mid of the tne- 

 ridian of the earth; 109. Measure^f time ; Objec- 

 tions; 110. Comparison of measures! Instruments for 

 measuring; 111. Micrometrical scales; Log lines; 11*. 



Lecture xx. On modelling, per- 

 spective, engraving, and print- 

 ing; 113. 



Copying a statue ; Modelling; Casting; 113. Per- 

 spective; Mechanical perspective ; 114. Geometri- 

 ci>l perspective; 115. Orthographical projection; 

 116; Projections of a sphere; 117. Invention of en- 

 graving; Woodcuts; 118. Mode of engraving; Rul- 

 ing; Mczzotinto; Etching; 119. Aqua tinta; 120. 

 Musical characters ; Printing; Copying letters ; Prmt- 

 ing from stones; 121. Letterpress ; Stereotype print- 

 ing; 122. 



Lecture xii. On statics; 123. 



Weighing; 123. English and French weights ; Ba- 

 lances; 124. False balances; 125. Weighing ma- 

 chines; Steelyards; Bent lever balances; 126. Spring 

 steelyard; Dynamometer; 127. Animal t actions ; 

 Strength of muscles; 128. Instances of strength; 

 Progressive motion ; 129. Running ; Pulling ; 130. 

 Sources of motion; Work of a labouring man; 131. 

 Temporary exertions; Horses; 132. Wind; Water; 

 Steam; 133. Gunpowder; Measurement of small 

 forces; 134. 



Lecture xiii. On passive strength 

 and friction ; 135. 



Immediate effects of force on a solid ; 135. Exten- 

 sion and compression; Rigidity; 136. Measure of 

 elasticity ; 137. Detrusion ; Lateral adhesion ; Flex- 

 ure; 138. Cause of irregularities; Stiffness; 139^ 

 Stiffness of beams; Hollow beams; Torsion; 140. 

 Alteration; Ductility; 141. Temper of metals; 

 Toughness; Britileness; 142. Fracture; Strength; 

 Resilience; Effect of velocity ; 143. Limit of strength 

 or resilience ; 144. Qualities of natural bodies; Frac- 

 ture by simple compression ; 145. Strength of lateral 

 adhesion ; Transverse force ; 146. Fracture by flex- 

 ure; Comparative strength and resilience; 14T. 

 Uses of resistonces of different kinds; Coach springs; 

 148. Comparison of direct and transverse strength ; 

 Beam cut out of a tree ; Hollow masts; 149. Strong- 

 est forms of beams; 150. Machine for measuring 



