254 HORTUS GRAMINEUS WOBURNENSIS. 



yearly expenses for repairs appear likewise to be from three 

 to nine shillings per acre. The value of such lands, by these 

 means, has been increased from one to twelve shillings (their 

 original value) to forty and sixty shillings per acre. But 

 when connected with a breeding flock of sheep, the 

 advantages derived from these meadows are hardly to be 

 estimated, for they produce a full bite of grass at least three 

 weeks earlier than the common pastures, and that at a 

 season vvhen every other kind of food is scarce. 



Irrigated meadows seldom or never require any manure, 

 the water being found sufficient to produce that extreme 

 degree of fertility for which they are remarkable. 



Sir H. Davy gives the theory of the effects of water in 

 increasing the fertility of meadows. He says they depend 

 on many causes, some chemical, some mechanical : — " When 

 land has been covered by water in the winter, or in the be- 

 ginning of spring, the moisture that has penetrated deep into 

 the soil, and even the subsoil, becomes a source of nourish- 

 ment to the roots of the plant in summer, and prevents those 

 bad effects that often happen in lands in their natural state, 

 from a long continuance of dry weather. 



" When water used in irrigation has flowed over a calca- 

 reous country, it is generally found impregnated with carbo- 

 nate of lime ; and in this state it tends in many instances to 

 ameliorate the soil. 



'' Even in cases where the water used for flooding is pure, 

 and free from vegetable or animal substances, it acts by 

 causing the more equable diffusion of the nutritive matter 

 existing in the land ; and in very cold seasons it preserves 

 the tender roots and leaves of the grass from being affected 

 by frost. 



" Water is of greater specific gravity at 42° Fahrenheit 

 than at 82°, the freezing point ; and hence, in a meadow 

 irrigated in winter, the water immediately in contact with 

 the grass is rarely below 40°, — a degree of temperature not 

 at all prejudicial to the living organs of plants. 



" In general, those waters which breed the best fish are 

 the best fitted for watering meadows ; but most of the bene- 

 fits of irrigation may be derived from any kind of water. 



