Scientific American Volume 78 Number 03 (January 1898) . THE JET FILE-DRIVER USED IN CONSTRUCTING THE TRESTLE them. They were 20 feet wide, 64 feet (the length offour bents) long and 5 feet thick. Those on the out-side were 20 feet by 20 feet in area and 3 feet in thick-ness. They were all built of brush and poles, with fiveor seven stops alternating in direction on the layers ofbrush and securely fastened by wire or rope to thepoles. The placing of the outside line of mattressesin position necessitated the construction of speciallaunching cars. These consisted of flat cars on whichframes or p
Scientific American Volume 78 Number 03 (January 1898) . THE JET FILE-DRIVER USED IN CONSTRUCTING THE TRESTLE them. They were 20 feet wide, 64 feet (the length offour bents) long and 5 feet thick. Those on the out-side were 20 feet by 20 feet in area and 3 feet in thick-ness. They were all built of brush and poles, with fiveor seven stops alternating in direction on the layers ofbrush and securely fastened by wire or rope to thepoles. The placing of the outside line of mattressesin position necessitated the construction of speciallaunching cars. These consisted of flat cars on whichframes or platforms measuring 20 by 24 feet were car-ried upon rollers. The mattresses were brought to thesite on these cars and, by means of a tripping gear and. DUMPING ROCK AFTER MATTRESSES HAVE BEEN LAID IN PLACE. tripping lines, the platform was given a sufficient pitchto slide the mattresses off into the water. The rock for the jetty was quarried on the banks ofthe Columbia River and towed in barges to the docksat the shore end of the structure. Here it was hoistedby steam derricks onto self-righting dump cars, of thepattern shown in the front page engraving, which carried from five to eight tons each. These were madeup in trains of ten or a dozen cars and hauled out tothe end of the jetty, where the rock was dumped ontothe newly laid mattresses. The dumping was done bymeans of a rack and pinion, and was so expeditiousthat two men could dump twenty cars of rock in fiveminutes. When the jetty was nearing completion,three spurs were run out for the pur-pose of protecting the shore line. Thefirst two were washed out by heavysurf, but the third attempt was moresuccessful, and a substantial break-water now extends from a point nearthe commence
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectwire, bookyear1898
