I. THE PITFALL, THE CLUB, THE SWORD, THE SPEAR AND DAGGER 50 II. POISON, ANIMAL AND VEGETABLE.--PRINCIPLE OF THE BARB 62 III. PROJECTILE WEAPONS AND THE SHEATH 74 IV. THE NET 85 V. REVERTED SPIKES 102 VI. THE HOOK.--DEFENSIVE ARMOUR.--THE FORT 115 VII. SCALING INSTRUMENTS.--DEFENCE OF FORT.--IMITATION.--THE FALL-TRAP 132 VIII. CONCEALMENT.--DISGUISE.--THE TRENCH.--POWER OF GRAVITY.--MISCELLANEA 144 ARCHITECTURE. I. THE HUT, TROPIC AND POLAR.--PILLARS AND FLOORING.--TUNNEL ENTRANCE OF THE IGLOO.--DOORS AND HINGES.--SELF-CLOSING TRAP-DOORS 159 II. WALLS, DOUBLE AND SINGLE.--PORCHES, EAVES, AND WINDOWS.--THATCH, SLATES, AND TILES 177 III. THE WINDOW.--GIRDERS, TIES, AND BUTTRESSES.--THE TUNNEL.--THE SUSPENSION-BRIDGE 190 IV. LIGHTHOUSES.--THE DOVETAIL.--THE DAM.--SUBTERRANEAN DWELLINGS.--THE PYRAMIDS.--MORTAR, PAINT, AND VARNISH 207 TOOLS I. THE DIGGING-STICK.--SPADE.--SHEARS AND SCISSORS.--CHISEL AND ADZE.--THE PLANE AND SPOKESHAVE 222 II. THE SAW AND ITS VARIETIES 239 III. BORING TOOLS.--STRIKING TOOLS.--GRASPING TOOLS 249 IV. POLISHING TOOLS.--MEASURING TOOLS 263 OPTICS. I. THE MISSIONS OF HISTORY.--THE CAMERA OBSCURA.--LONG AND SHORT SIGHT.--STEREOSCOPE AND PSEUDOSCOPE.--MULTIPLYING-GLASSES 276 II. THE WATER-TELESCOPE.--IRIS OF THE EYE.--MAGIC LANTERN.--THE SPECTROSCOPE.--THE THAUMATROPE 291 USEFUL ARTS. I. PRIMITIVE MAN AND HIS NEEDS.--EARTHENWARE.--BALL-AND-SOCKET JOINT.--TOGGLE OR KNEE JOINT 308 II. CRUSHING INSTRUMENTS.--THE NUT-CRACKERS, ROLLING-MILL, AND GRINDSTONE.--PRESSURE OF ATMOSPHERE.--SEED DIBBLES AND DRILLS 320 III. CLOTH-DRESSING.--BRUSHES AND COMBS.--BUTTONS, HOOKS AND EYES, AND CLASP 339 IV. THE STOPPER, OR CORK.--THE FILTER 350 V. THE PRINCIPLE OF THE SPRING.--THE ELASTIC SPRING.--ACCUMULATORS.--THE SPIRAL SPRING 360 VI. SPIRAL AND RINGED TISSUES.--VARIOUS SPRINGS IN NATURE AND ART 375 VII. FOOD AND COMFORT 390 VIII. DOMESTIC COMFORT 400