100 



On the Economical Manufactory of 



rally give him sufficient experience to enable him to turn off 3000 

 tiles per day. 



Having now given a detailed statement of the mode of manu- 

 facturing and the cost of producing tiles in this county, with a 

 general statement of the construction of a tile work or tile and 

 brick work, it would be useless for me to attempt to give a theo- 

 retical direction as to the burning of tiles, this part of the work 

 being purely practical. None but experienced burners can tell 

 from the appearance of the flues and fires of a kiln, how to regu- 

 late the heat or management of them with supplies of different 

 sorts of fuel. 



I would observe that the clay best adapted for tiles is that 

 which contains a small proportion of sand or marl, or sand may 

 be mixed with the clay when raised in the winter. Clay thus 

 mixed does not contract so much in drying, and the tiles, when 

 burnt, are larger and sounder; but as tiles must be made from 

 clay beds in the locality where they are required for use, it will 

 be expedient to consult practical men acquainted with the soil. 



In conclusion, I wish to add a few observations upon furrow 

 draining on tenacious clay soils ; the drainage of these soils has 

 generally been done in shallow depths, under the prevailing 

 common opinion that otherwise the water would not get into the 

 drains. The contraction which beds of clay undergo when cut 

 through by parallel drains has thus been entirely overlooked. 

 This contraction, however, is most important, so much so (as I 

 have found by experience) that drains dug from 30 to 40 inches 

 deep have operated to much greater advantage than those of shal- 

 lower depth. The bed of clay contracts itself near the drains as 

 deep as the drains are made ; and the deeper the bed of clay is 

 contracted, the larger will be the fissures for the water to per- 

 colate through to the drains. In well-drained land, the water 

 does not enter the drain by the furrow, but percolates through the 

 fissures (formed by contraction) from the ridge to the drains. It 

 is also, I consider, an error to cover tiles with loamy soil or vege- 

 table substances ; these have a tendency, after a few years, to 

 choke the drains : the best covering upon them is the clay itself. 

 The action of the atmosphere will always so contract the clay, 

 that there will be sufficient fissures for carrying the water into 

 the drains. This is proved by the system of block-draining, which 

 is sometimes performed on very strong clays in this county. The 

 plan is to dig out the drain, lay a block of wood in the bottom of 

 the drain, then beat the clay firmly upon the block, and after 

 drawing forward the block the same operation is repeated. Now 

 there is no complaint that the water does not enter these drains, 

 for the contraction of the clay which always takes place remedies 

 the supposed obstruction. 



