^ THE IMPROVEMEXT OF RIVERS. 



barge cables is now taken in from the bank and the strain equalized. They are then 

 fastened permanently with clamps, as are also the mattress head-lines. An entire 

 shift 22 feet long is then launched, a new set of weaving-poles being spliced to the pio- 

 jecting ends of the first set. This is continued as described to within 2 feet of the top 

 of the second set of poles, when another launch is made, and so on, until the full length 

 of the mattress is obtained. 



When three shifts have been launched the construction of a top grillage or frame- 

 work is begun. This consists of a line of poles laid over and parallel with the weaving- 

 poles, lapping each other, butts to tops, from 6 to 8 feet, and wired to the weaving- 

 poles every 4 feet by lashings 2 feet long, made of two strands of No. 10 wire; transverse 

 poles 8 feet apart for the first 100 feet, and thereafter 16 feet apart, are placed in similar 

 manner and fastened to the longitudinal ones at the intersections by two-feet lashings 

 made of four strands of No. 1 2 wire. 



The purpose of the grillage is to make pens in which the stone is retained, as well 

 as to strengthen the construction. The first set of transverse poles along the inner edge 

 are hardwood, set 8 feet apart throughout the length of the mat, and are used to con- 

 nect the shore mat, which is also being built, to the river mat. 



The construction of the shore mat is as follows: Hardwood poles of the size of the 

 weaving poles are lashed and spiked to the river mattress, and willow or cotton-wood 

 poles are spliced to these until they reach up the slope about 40 feet. Alongside and 

 fastened to each of the hardwood poles is a cable made of eight strands of No. 10 wire, 

 one end of which is fastened to two of the adjacent weaving-poles, and the other to the 

 willow poles extended on the slope. Upon the transverse poles are laid longitudinally 

 willow or cotton-wood poles 8 feet apart, beginning with the first set about 4 feet from 

 the edge of the mat. The latter poles are wired to the former at their intersections. 

 The longitudinal poles are carried on lines 8 feet apart up to the top of the slope, and 

 on their lower side, 8 feet apart, are driven stakes a feet 6 inches above the ground, to 

 the tops of which is loosely fastened a lashing of wire whose bight has first been passed 

 under the pole. These stakes are used down to the pole nearest the water edge. Upon 

 this framework is laid willow brush diagonally with the butts toward the top of the 

 slope and breaking joints throughout. A second layer of brush is put on in the opposite 

 direction, the two thus being at right angles to each other. On top of these layers a 

 second pole framework, fastened similarly to the first, is placed and fastened down 

 firmly by the lashings mentioned above as being tied to the stakes. As fast as the 

 river- and shore-work is finished transverse cables arc run across the entire width of the 

 mat at 1 6-foot intervals, carried to. top of bank, and hauled taut and fastened to trees, 

 stumps, or deadmen placed for the purpose. These are fastened to the mat every 16 

 feet with lashings. 



When 400 or 500 feet of river mattress have been completed, longitudinal cables 

 are run out from the mooring barges and securely attached to the mat at i6-foot inter- 



