100 



Geology of the Keythorpe Estate. 



The next object is to connect these furrows bj drains laid 

 across them. The result is, that as the furrows and ridges here 

 run along- the fall of the ground, which I have observed to be 

 the case generally elsewhere, the submains follow the fall, and 

 the parallel drains cross it obliquely. 



The intervals between the parallel drains are irregular, vary- 

 ing, in the same field, from 14 to 21, 31, and 59 feet. The 

 distances are determined by opening the diagonal drains at the 

 greatest distance from the trial-holes, at which experience has 

 taught the practicability of its draining the hole. If it does not 

 succeed in accomplishing the object, another drain is opened in 

 the interval. It has been found, in many cases, that a drain 

 crossing the clay-banks and furrows takes the water from holes 

 lying lower down the hill ; that is to say, it intercepts the water 

 flowing to them through these subterranean channels. The 

 parallel drains, however, are not invariably laid across the fall. 

 The exceptions are on ground where the fall is very slight, in 

 which case they are laid along the line of greatest descent. On 

 such ground there are few or no clay-banks and furrows. 



The greater part of the estate had previously been drained 

 with drains 2 to 2^ feet deep, laid along the line of greatest 

 descent, and they had proved a complete failure. The present 

 system has stood the test of about 15 years' experience ; and of 

 its efficiency there can be no question. Lord Berners does not 

 consider a field sufficiently drained till sheep can consume the 

 turnips on the ground upon these strong soils without poaching 

 the land. The difference in the texture of the soil before and 

 after draining is very remarkable. A tenacious clay appears 

 converted into a friable loam. With regard to the economy of 

 the system, that will be best shown by comparing it with that 

 of equidistant drains, laid along the declivity at the distances 

 suited to such a soil, stating the difference between the two 

 systems in perches of drain and hundreds of tiles per acre. By 

 these means the calculation is freed from all complexity arising 

 from local variations in the wages of labour and cost of pipes, 

 tiles, or broken stones. The saving in length of drain and 

 quantity of materials for forming the conduit, are constant quan- 

 tities for that description of soil, wherever situated ; the money 

 value of labour and materials varies in different localities. There 

 are, moreover, great discrepancies in practice with respect to the 

 nature of the conduit. Some prefer pipes of an inch bore, some 

 like larger diameters ; some advocate cylindrical pipes, others 

 pipes with a flat sole ; some prefer them with collars, some 

 without ; while others think sufficient water-way cannot be 

 obtained except with the old horseshoe tiles and soles. Lastly, 

 there are some localities to which broken stones are better 



