$4 APPENDIX. 



The back, or ftagnated water, is the beft guide to 

 point out the courfe for introducing the excavations or 

 difcharges into the river ; it has, however, been often 

 found ncceflary to attend to accurate levels along the 

 banks : for inftance, if the fall from b, to c t was found 

 inconfiderable, it might be encreafed, by letting the 

 end of the excavation fall into the river at d t iufiead of 



at*. '^-l 



It is plain that, when the water fubfides in the river, 

 the waters of the flats and plains will fall into the ex- 

 cavations, and from thence be immediately carried into 

 the river, and all behind laid perfectly dry in a few 

 hours, which has been invariably the cafe here for 

 many years back. 



This work is always performed in the fpring feafon, 

 in order that the furface may be completely fwarded 

 over, before the autumnal rains fet in. With refpect 

 to fwarding, or creating a new furface for thofe exca- 

 vations, the beft mode by far is, to make ufe of the 

 old furface ; but, inftead of laying it on in regular 

 uniform fods, it fhould be chopped into a number of 

 fmall pieces, anJ firmly beaten together by the back of 

 the fpade. Experience has, on many occafions here 

 of making new furfaces, fhewn the fuperiority of this 

 practice over all others, in point of (lability and firm 

 texture ; but it fiiould be attended to early in the fea- 

 fon, othcrwife it cannot fucceed ; befides, the old fur- 

 face goes further when thus treated. The excavations, 



above 



