Report on Drain - Tiles and Drainage. 
379 
tion of this fact that the pipe-tile of the eastern counties, and Mr. 
Etheredge's small tiles and covers, can be applied with such a re- 
markable economy in comparison with the old tile, and with most 
other materials hitherto employed in drainage. An advantage 
incidental to the use of tiles and pipes of small bore is, that neither 
the mole nor the rabbit — those pests of the farmer — can enter 
them. The chief enemies to guard against are the roots of trees, 
particularly those loving moisture. Mr. Hammond has observed 
the roots of the water-willow to penetrate a rod in length up 
drains ; outfalls, therefore, should be so managed that no fence, 
trees, or shrubs can mar the working of the drain. 
Durability. — Time is the only criterion for forming a perfect 
estimate of the durability of such an article as the drain-tile ; but 
density and toughness are acknowledged tests of good pottery ; 
and it can scarcely be questioned that the densest tile will endure 
the longest in the ground. After a careful investigation of the 
solid contents and weights of the tiles registered in the Table, the 
following facts appear as regards their density : — 
Weight. 
Oz. 
Tweeddale . 0 973 per cubic inch of matter. 
Etheredge .1-091 „ 
Read, No. 1 . 1 • 138 „ 
2 . i-n4 
3 . 1-204 
„ . 4 . 1-322 
5 . 1-401 
These results seem to be in strict conformity with the degree of 
preparation of the earth, as well as with the nature and amount 
of the force to which the respective tiles are subjected in the 
apparatus employed ; and it is seen that the density of the cylin- 
dric tile increases in the inverse ratio of the magnitude of the 
orifice through which the clay is expressed from the cylinder. It 
must, however, be borne in mind that, in order to render compa- 
risons of this kind free from error, the clay of differently made 
tiles should be alike ; whereas in the foregoing examples the 
articles were manufactured in separate counties, and from earth 
of different quality. 
