The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . k of the was by far the longest tunnel in the wodd, being more than3-I m. in length, and was driven under Monte Salviano, whichnecessitated shafts no less than 400 ft. in depth. Forty shaftsand a number of cuniculi, or inclined galleries, were sunk,and the excavated material was drawn up in copper pails, ofabout ten gallons capacity, by windlasses. The tunnel wasdesigned to be 10 ft. high by 6 ft. wide, but its actual cross-section varied. It is stated that 30,000 labourers were occupiedel
The encyclopædia britannica; a dictionary of arts, sciences, literature and general information . k of the was by far the longest tunnel in the wodd, being more than3-I m. in length, and was driven under Monte Salviano, whichnecessitated shafts no less than 400 ft. in depth. Forty shaftsand a number of cuniculi, or inclined galleries, were sunk,and the excavated material was drawn up in copper pails, ofabout ten gallons capacity, by windlasses. The tunnel wasdesigned to be 10 ft. high by 6 ft. wide, but its actual cross-section varied. It is stated that 30,000 labourers were occupiedeleven years in its construction. With modern appliancessuch a tunnel could be driven from the two ends withoutintermediate shafts in eleven months. No practical advance was made on the tunnelling methods ofthe Romans until gunpowder came into use. Old engravingsof mining operations early in the 17th century show thatexcavation was still accomplished by pickaxes or hammer andchisel, and that wood fires were lighted at the ends of theheadings to split and soften the rock in advance (see fig. i).. (From Agricolas De re melcJlUa, Basel, 1621.) Fig. I —Method of mining, methods of ventilation by shaking cloths in the headingsand by placing inclined boards at the top of the shafts are alsoon record. In 1766 a tunnel 9 ft. wide, 12 ft. high and 2880 was begun on the Grand Trunk Canal, England, andcompleted eleven years later; and this was followed by manyothers. On the introduction of railways tunnelling became oneof the ordinary incidents of a contractors work; probablyupwards of 4000 railway tunnels have been executed. Tunnellingundcr Riversand Harbours.—In 1S25 MarclsambardBrunei began, and in 1843 completed, the Thames tunnelbetween Rotherhithe and W^apping now used by the EastLondon railway. He employed a peculiar shield, made oftimber, in several independent sections. Part of the groundpenetrated was almost liquid mud, and the cost of the tunnelwas about
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
