II. METHODS OF DETERMINING THE CENTER LINE AND FORMS AND DIMENSIONS OF CROSS-SECTION 9 III. EXCAVATING MACHINES AND ROCK DRILLS; EXPLOSIVES AND BLASTING 22 IV. GENERAL METHODS OF EXCAVATION; SHAFTS; CLASSIFICATION OF TUNNELS 36 V. METHODS OF TIMBERING OR STRUTTING TUNNELS 47 VI. METHODS OF HAULING IN TUNNELS 59 VII. TYPES OF CENTERS AND MOLDS EMPLOYED IN CONSTRUCTING TUNNEL LININGS OF MASONRY 66 VIII. METHODS OF LINING TUNNELS 72 IX. TUNNELS THROUGH HARD ROCK; GENERAL DISCUSSION; REPRESENTATIVE MECHANICAL INSTALLATIONS FOR TUNNEL WORK 84 X. TUNNELS THROUGH HARD ROCK (_continued_); EXCAVATION BY DRIFTS; THE SIMPLON AND MURRAY HILL TUNNELS 102 XI. TUNNELS THROUGH HARD ROCK (_continued_); EXCAVATION BY HEADINGS 130 XII. EXCAVATING TUNNELS THROUGH SOFT GROUND; GENERAL DISCUSSION; THE BELGIAN METHOD 143 XIII. THE GERMAN METHOD--EXCAVATING TUNNELS THROUGH SOFT GROUND (_continued_); BALTIMORE BELT LINE TUNNEL 155 XIV. THE FULL SECTION METHOD OF TUNNELING; ENGLISH METHOD; AMERICAN METHOD; AUSTRIAN METHOD 166 XV. SPECIAL TREACHEROUS GROUND METHOD; ITALIAN METHOD; QUICKSAND TUNNELING; PILOT METHOD 182 XVI. OPEN-CUT TUNNELING METHODS; TUNNELS UNDER CITY STREETS; BOSTON SUBWAY AND NEW YORK RAPID TRANSIT 195 XVII. SUBMARINE TUNNELING; GENERAL DISCUSSION; THE SEVERN TUNNEL 218 XVIII. SUBMARINE TUNNELING (_continued_); THE COMPRESSED AIR METHOD; THE MILWAUKEE WATER-WORKS TUNNEL 225 XIX. SUBMARINE TUNNELING (_continued_); THE SHIELD SYSTEM 238 XX. SUBMARINE TUNNELING (_continued_); THE SHIELD AND COMPRESSED AIR METHOD; THE HUDSON RIVER TUNNEL OF THE PENNSYLVANIA RAILROAD 263 XXI. SUBMARINE TUNNELING (_continued_); TUNNELS AT VERY SHALLOW DEPTH; THE COFFERDAM METHOD; THE PNEUMATIC CAISSON METHOD; THE JOINING TOGETHER SECTIONS OF TUNNELS BUILT ON LAND 281 XXII. ACCIDENTS AND REPAIRS IN TUNNELS DURING AND AFTER CONSTRUCTION 301 XXIII. RELINING TIMBER-LINED TUNNELS WITH MASONRY 315 XXIV. THE VENTILATION AND LIGHTING OF TUNNELS DURING CONSTRUCTION 325