Popular science monthly . cable should snap, the crib would be dashed topieces on the rocks below the falls THE work oflui i 1(1 ingcctTcr-danis, ort e m p o r a r ydams, is oftenas ticklish anddifficult as thelarger and sup-posedly moreimportant fin-ished pivcc ofconstructionwhich is impos-sible withoutthe dams as afoundation. The pictureillustrates the placing of a section of the crib-work ofa coffer-dam. Observe that the wateris in almost flood state, because thenatural channel of the river has been somuch restricted by the already com-pleted part of the work. The cribs are built on dry lan
Popular science monthly . cable should snap, the crib would be dashed topieces on the rocks below the falls THE work oflui i 1(1 ingcctTcr-danis, ort e m p o r a r ydams, is oftenas ticklish anddifficult as thelarger and sup-posedly moreimportant fin-ished pivcc ofconstructionwhich is impos-sible withoutthe dams as afoundation. The pictureillustrates the placing of a section of the crib-work ofa coffer-dam. Observe that the wateris in almost flood state, because thenatural channel of the river has been somuch restricted by the already com-pleted part of the work. The cribs are built on dry land toverj^ accurate measurements. When allis ready, each one is laimched in itsorder. The methods of control, afterlaunching, vary. In this case five steelwire cables of ^s-i. diameter rigidlyconnected with five winches, located atpoints on the river banks, were used tocontrol the course of the cribs as theywere placed. When a new section isbrought in line with the already existing Popular Science MonthlyA Ticklish Moment. To ascertain the time, simply pull the watch down out of its case. The spring will withdraw it when released 29 work, it is heldfast there bythe cables andwinches untilthe rock, piledat the end ofthe older partof the dam,is thrown intothe spaces inthe crib andthe new sectionis thus weigh-ted into thecablesand all otherlashings areremoved andthe section treated in like of the extent of the forcesthat have to be met with, due to the im-mense water pressure, may be gatheredfrom the fact that during the placingof one of these cribs, one cable partedand the strain thus thrown upon theremaining four proved successively toomuch and they each in turn gave crib meantime sailed gaily downstream, o\er the rocks and bumps ofthe falls below. Where coffer-dams arc thrown acrossdeep channels of treacherous waters thework is fraught with the greatest danger,necessitating the most careful system ofoperations. A Protecting Holder for an
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872
