37 



tow his barges (PL II., fig. n) to his concession, a great 

 economy both of time and labour. If the bottom be 

 firm and well consolidated the weight of tiles within is 

 sufficient to keep the ruche in position. More frequently 

 the ground chosen is soft and muddy and piles have to 

 be driven well down to form a foundation for the ruche 

 and prevent it sinking partially into the mud. For each 

 ruche usually 6 piles are used, driven in until the upper 

 ends are a few inches above the surface of the mud. On 

 these the ruche is placed and securely nailed thereto. To 

 obtain further rigidity should the mud be specially soft 

 or the position somewhat exposed, side stays or struts 

 are used to give support (Fig. 4). The struts are pine 

 props driven by hand into the mud obliquely for some 2 

 feet or more and so placed that the upper edge of the 

 ruche rests upon them ; a nail driven through the ruche 

 frame into the head of the prop prevents displacement. 



The ruches are disposed at right angles to the margin 

 of the channel they border as this interferes with the 

 current more effectually than in any other disposition ; 

 eddies and quiet waters are the consequence and such by 

 delaying the current-driven spat give greater opportunity 

 for it to settle and attach upon the tiles. According to 

 the width of the ground available, the ruches are arranged 

 in two or in three rows ; between each two rows sufficient 

 space is left for a man to pass. 



In stacking the tiles in the ruches, the lowermost 

 row is laid transversely, the ends of each tile supported 

 upon the longitudinal bars of the bottom frame of the 

 ruche (PL III, fig. 12), which is made of a size into 

 which the tiles just fit comfortably when laid transverse 

 to the length of the case. Care is taken not to allow 

 adjoining tiles to touch one another ; a space of from 

 3 to 4 centimetres is given between them. Nine tiles 

 go usually to form a transverse row. The remainder of 

 the tiles are laid in rows alternately longitudinal and 

 transverse, the concave surface always downwards. 

 A ruche of the usual size accommodates 100 tiles. 



