If a cable should snap, the crib would be dashed to 

 pieces on the rocks below the falls 



THE work of 

 lui i 1(1 ing 

 cctTcr-danis, or 

 t e m p o r a r y 

 dams, is often 

 as ticklish and 

 difficult as the 

 larger and sup- 

 posedly more 

 important fin- 

 ished pivcc of 

 construction 

 which is impos- 

 sible without 

 the dams as a 

 foundation. 



The picture 

 illustrates the 



placing of a section of the crib-work of 

 a coffer-dam. Observe that the water 

 is in almost flood state, because the 

 natural channel of the river has been so 

 much restricted by the already com- 

 pleted part of the work. 



The cribs are built on dry land to 

 verj^ accurate measurements. When all 

 is ready, each one is laimched in its 

 order. The methods of control, after 

 launching, vary. In this case five steel 

 wire cables of ^s-'i. diameter rigidly 

 connected with five winches, located at 

 points on the river banks, were used to 

 control the course of the cribs as they 

 were placed. When a new section is 

 brought in line with the already existing 



Popular Science Monthly 

 A 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 held 

 fast there by 

 the cables and 

 winches until 

 the rock, piled 

 at the end of 

 the older part 

 of the dam, 

 is thrown into 

 the spaces in 

 the crib and 

 the new section 

 is thus "weigh- 

 ted into place." 

 Then thecables 

 and all other 

 lashings are 

 removed and 

 the ne.xt section treated in like manner. 

 Something of the extent of the forces 

 that have to be met with, due to the im- 

 mense water pressure, may be gathered 

 from the fact that during the placing 

 of one of these cribs, one cable parted 

 and the strain thus thrown upon the 

 remaining four proved successively too 

 much and they each in turn gave way. 

 The crib meantime sailed gaily down 

 stream, o\er the rocks and bumps of 

 the falls below. 



Where coffer-dams arc thrown across 

 deep channels of treacherous waters the 

 work is fraught with the greatest danger, 

 necessitating the most careful system of 

 operations. 



A Protecting Holder for an 

 Open-Faced Watch 



WE illustrate an original idea in a 

 watch-holder for wearing upon 

 the person, especially for ladies' use, in 

 which the watch is invisible and is 

 jHilled down by a suitable pendant so 

 as to allow the face to be seen. The 

 illustration shows the holder as seen 

 from the back, with the watch partly 

 drawn down and out of the holder 

 against the top spring. A crescent- 

 shajjed piece receives the watch when 

 drawn up. The watch may be of special 

 shaped as here shown, or a flat disk can 

 be used to serve as a watch-carrier, 

 with an ordinary watch fitted into it by 

 clamps. In this case the disk works 

 with the spring and the pendant, allow- 

 ing any watch of proper size to be fitted 

 into it and carried with safety. 



