A 'PRACTICAL' BEGINNING. 15 



the best illustration of this underground mischief. 

 Nothing can look smoother and more even than the 

 bottom, till that uncompromising test of accurate 

 levels, the Water, makes its appearance : all on 

 a sudden the whole scene is changed, the eye- 

 accredited level vanishes as if some earthquake 

 had taken place : here there is a gravelly Scour 

 along: which the stream rushes in a thousand little 



O 



angry-looking ripples; there it hangs, and looks 

 as dull and heavy as if it had given up running at 

 all, as a useless waste of energy ; in another place, 

 a few dead leaves or sticks, or a morsel of soil 

 broken from the side, dams back the water for a 

 considerable distance, occasioning a deposit of soil 

 along the whole reach, greater in proportion to the 

 quantity and the muddiness of the water detained. 

 All this shows the paramount importance of perfect 

 evenness in the bed on which the tiles are laid. 

 The worst-laid tile is the measure of the goodness and 

 permanence of the whole drain, just as the weakest 

 link of a chain is the measure of its strength. 



But this, of course, was all theory ; and theory, of 

 course, was all nonsense : my practical head-drainer 

 was quite of a different way of thinking, as his 

 modus operandi will exhibit. The morning after he 



