I 209 ] 

 trap-door at the bottom of the fubterrane- 

 oils canal may then be opened, and all the 

 water let out for repairing any of the works -, 

 it runs into the channel, g. 



I mould, in the next place, remark, that 

 the water marked H, H, H, H, is the river 

 Mediae k, and I, the Duke's canal ; but as 

 it is the firft and grand principle of Mr. 

 Brindleys plan, with all artificial naviga- 



terfrom thefe fhall fall in at right angles, the earth, 

 will wreck, and be apt to fill up, and fpoil the 

 drain. Stones, or brick, fhould likewife be put 

 over the fmaller, for a foot or two before they 

 join the main drain ; and the place where they 

 join ihould be well fecured. Plate VI. Fig. 1. 

 A the main drain. B'B the lefTer ones. 

 The lejfer Drains are thus made. 



Firft, with a common ipade take out the turf, 

 or fods, eighteen inches wide, and of a fumcient 

 thicknefs, and lay them on one fide, with great 

 care : then with the fame fpade fink two or three 

 fpits deeper, at the lame width, and throw the 

 earth on the other fide •, and take care that th^ 

 fides and bottom of this trench be worked off 

 fmooth and clean -, then take a board near eigh- 

 teen inches wide, and fifteen feet long, or twen- 

 ty, as it fuits, with a flit in the middle of four 

 inches wide : or, rather two boards of the fame 

 dimenfions, put together as under. Plate VI. 

 Fig. 2. B B are two crofs pieces on the upper 

 fide, to fallen the boards together. 



This board lays flat on the bottom of the 

 trench, and the man ftands upon it, and with 

 the narrow long tool, Plate VI. Fig. 3. he 

 "works the drain with great expedition, exactnefs, 

 and eafe, and, if he Jets out right, is always fure 



Vol, .III. P of 



