178 Improved System of laying out Catch-Meadoios. 



compared with the pipe system in the recent able reports pub- 

 lished by the Board of Health, as if their effects were at all similar. 

 Whatever be the merits of the pipe system, its object is an entirely 

 distinct one. The primary object in forming water-meadows, it 

 cannot be too strongly insisted, is to distribute water in winter 

 over ground which is already moist, not to convey liquid in 

 summer into ground which is dry. Nay, this latter object is 

 altogether protested against by many farmers, as by Mr. Bickford 

 in his present paper, from a fear of giving rot to the sheep. 



The mode in which irrigation benefits meadows is still 

 doubtful ; but I have no doubt whatever that the phenomenon 

 is a complex and not a simple one : I mean that the causes of 

 action are more than one, or even than two. It is important to 

 clear up this point, as by so doing we shall then understand 

 better how to proceed with the investigation in future. The 

 deposition of solid matter held in suspension is unquestionably 

 one principal mode of action, but assuredly not the only one, for 

 a clear spring issuing from the hill-side sometimes begins to act 

 at once upon vegetation as it were from the cradle. Not only 

 are the Vi^aters of a muddy river and of a crystal brook different, 

 but as Sir Stafford Northcote's gutterer, Mr. Ellis, informed me, 

 the effect is distinct and sometimes opposite. A thick stream, 

 experience shows, improves the condition of land — a clear 

 stream may even impoverish the soil, though it brings the 

 grass forward. There is no paradox here, if we consider that 

 the turbid water adds permanently to the soil : the clear water, 

 by stimulating the herbage, occasions elements of vegetable 

 life to be withdrawn from it. If successive crops then be re- 

 moved without any return of manure, the natural result will be 

 impoverishment. 



It is certain, moreover, that clear water itself has two modes 

 of action. First, by salts it may hold in solution, ammonia for 

 instance derived from the farmyard, and very probably also 

 ammonia brought up by deep-seated springs from the depths of 

 the earth. Here let me remark, since landowners have, I know, 

 been deterred from attempts at irrigation by the absence of lime 

 from their streams, that while on the one hand streams flowing 

 from chalk-hills are undoubtedly good, softness on the other 

 hand is the test of the best water in Devonshire, the classic land 

 of hill- side irrigation. 



The remaining cause of action is certainly warmth, and even 

 here the action may be also a double one. Warm springs, it is well 

 known, are the most effective, imparting, no doubt, their tem- 

 perature to the ground ; but all streams probably, when made 

 to pass over land, impede the radiation of heat, that is check 

 the escape of Vv'armth from the ground. 



