166 



Improved System of Irrigation. 



the gutter should drop that way accordingly (and in proportion), 

 and be of a good size; but if the water is wanted chiefly at the 

 beginning end of the gutter, the drop need not be so much, and 

 the gutter should taper away so as to end nearly in a point. 



The next consideration should have regard to the size of the 

 stream. If it is enough to water the whole piece at all times, 

 one gutter, of sufficient size to do the work, should be made ; and 

 to do it without stops ; stops in a gutter are decidedly objection- 

 able. Where the stream is small, make a leading gutter, and 

 take out from it taper gutters, each of a size suited to the stream 

 when at its smallest, so that when the stream increases (from 

 rain or any other cause), so many taper gutters may be used as 

 will disperse the whole stream. The leading gutter should con- 

 tinually decrease in size from the beginning to the end, ^. e., from 

 the place where the first taper gutter is taken out of it, and 

 finish in a tapering water-gutter itself at last {see fig. 4). 



Fig. 4. 



A c B 



A B is a carriage-gutter as far as and a watering gutter 

 from c to B : <2 and h are watering gutters taken out of it. 

 When the stream is small, a stop at 1 will cause it to work in 

 a ; a stop at 2 will work in b ; without any stop it will 

 work in c B. If the stream is too much for c B, it will work 

 h at the same time ; and should there be water enough, it will 

 also fill a without any stop at all. Care should be taken not 

 to make A B larger than just to carry the full stream wanted ; 

 and in every case when the gutter is got too large by frequent 

 cleaning out, cut it anew on one side or the other. 



In levelling, after having marked every 2 poles with the spirit- 

 level, mark the ground between with the plumb-level every 10 

 feet or so, and cut accordingly. Make the hedgetrough a carriage- 

 gutter wherever it can be done conveniently, taking care always 

 to make the water run in them when so used ; and by no means 

 to have stagnant water in the troughs. Covered gutters made 

 with large tile could also be substituted for the deep open 

 carriage-gutter, where it is necessary to cross the middle of 

 meadows ; it would thus obviate the danger of the open gutter 

 to sheep and lambs ; and the extra expense would be partly com- 

 pensated, as the tiled gutter would never require the annual 

 " cleaning outP 



General rules cannot be laid down to suit every circumstance 

 that will occur, but practice and an ingenious mind will decide 

 that which is most fitting on each occasion. 



