. St. Nicholas [serial]. ON THE VIADUCT OF HCGE ARCHES. bankment. Channels were first dug so as to pro-vide a depth of two and one half feet of these the two dredges slowly made their way,each digging its own channel deeper. They piledup between them the material thus dredged out,and with it formed the road-bed. The progressof the dredges was hampered and delayed inmany places by the rocks, which came so near thesurface as to necessitate the construction oflocks to float the dredges over them. Nearlythirty islands are utilized for short stretches ofthe construction, the longest being
. St. Nicholas [serial]. ON THE VIADUCT OF HCGE ARCHES. bankment. Channels were first dug so as to pro-vide a depth of two and one half feet of these the two dredges slowly made their way,each digging its own channel deeper. They piledup between them the material thus dredged out,and with it formed the road-bed. The progressof the dredges was hampered and delayed inmany places by the rocks, which came so near thesurface as to necessitate the construction oflocks to float the dredges over them. Nearlythirty islands are utilized for short stretches ofthe construction, the longest being sixteen milesQn Key Largo. More than fifty miles of rockand of earth embankment had to be put in wherethe water is shallow, but, where the water isdeeper and the openings exposed to storms bybreaks in the outer reef, concrete viaducts were igi2.] NATURE AND SCIENCE FOR YOUNG FOLKS 847. AN EXPRESS-TRAIN GOING OUT TO SEA OVER THE ARCHED VIADUCT. built, consisting o-f arch spans and piers, or steelbridges resting on concrete piers, some spans ofthe latter being two hundred and forty feet. Thiswas the most difficult part of the work. The wa-ter is from ten to thirty feet deep, and the bottomis coralline rock. There are twenty-eight ofthese arch viaducts, aggregating ten and eighttenths miles in length, and eight steel bridges,aggregating six and one tenth miles in length. The longest viaduct is between Knights Keyand Little Duck Key, seven miles, and is calledthe Knights Key Viaduct. In many places theembankment for the roadway is eight or ninefeet in height, the road-bed being ballasted withcoralline limestone, of which these islands arecomposed. This makes a very strong, safe road. Tn many places where the water is deep enough to float an ocean steamship of large size, andwhere the locality is exposed directly to the galesfrom the Atlantic, much of the work has beenpe
Size: 2505px × 997px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthordodgemar, bookcentury1800, bookdecade1870, bookyear1873
