310 MAY. 



llth, When the levels are taken, in examining 

 all the lands below them, the main point (in 

 which errors are perpetually made) is to determine 

 where to begin. If there be water sufficient, all 

 should certainly be done ; but, supposing a choice 

 tiecessary to make, whether from insufficiency of 

 water to do the whole, or from any other causc 5 

 then the operator must exercise his judgment ; 

 and in making his estimation, he is to attend to 

 the following circumstances : 



1. The expence of digging his grand carriers on 

 the levels first taken, which should be large enough 

 to take the whole stream on either side the vale at 

 pleasure; but if the lands on one side are more 

 favourable for watering than on the other, let that 

 carrier be executed first. If the most favourable 

 land to work upon on such side, be at a great dis- 

 tance from the prise cTeau, or original spot where 

 the water is first taken, and there be not water for 

 the whole below the level on one side of the river, 

 then he must compare the expence of the carrier 

 with the superiority of the profit of watering the 

 most favourable fields, rather than others nearer 

 not offering in themselves an equal advantage. In 

 most cases, the benefit of watering at pleasure is 

 greater than the expence of making the carrier. 

 And in this point there is also another considera- 

 tion of great moment : though the river may not 

 afford plenty of water in summer, or very dry years, 

 yet it may abound in winter, and watering at that 

 season alone is well worth the expence of all the 



neccs- 



