No. 16. 



Draining — JSt^o. 2. 



313 



a hand-sketch of the piece of ground to be 

 drained, marking each line as it is laid off in 

 the field, and noting the depth and direction 

 in which the water is to run. 



The lines being marked off in the manner 

 described, these are to form the upper edges 

 of the drains. 



The width of the drain at the top depends 

 upon its depth, it being usual, except in the 

 case of very hard and tenacious substances, to 

 make it slope from the top to the bottom. — 

 Thus, if it be six feet deep, and from 18 in. 

 to 2 feet wide at bottom, it may be 2^ feet 

 wide at top. 



The workman, in forming the trench, 

 works up to the higher ground, and never 

 from the higher ground to the lower. The 

 instruments which he uses in the operation 

 are — the common spade, a shovel for throwing 

 out loose substances, a pick or mattock, for 

 raising stones and breaking the earth when 

 hard, and the foot-pick. 



The materials to be used for filling the 

 drain may be stones, tiles, or other hard and 

 durable substances. When stones are to be 

 employed, if they are inconveniently large, 

 they may be broken to the weight of three or 

 four pounds. They may be laid down for 

 use, before the cutting of the drain is begun, 

 along the upper line of the drain, the earth 

 being thrown by the workmen to the lower 

 side; or else they may be brought forward 

 while the work is going on, and thrown from 

 the cart into the drain. 



In the larger class of drains it is regarded 

 as beneficial, and even necessary, to form a 

 conduit at the bottom. This is done by 

 building a little wall roughly on each side at 

 the bottom, about six inches in height, and so 

 as to leave an aperture or conduit of about six 

 inches in width. The workman then covers 

 it with such flat stones as he can procure, fil- 

 ling up also the interstices of these covers 

 with smaller stone?, so as to defend the con- 

 duit from earth and other substances that 

 miglit fall into it. When this is done, the 

 remaining stones are thrown in promiscuous- 

 ly to the height of 18 inches or two feet above 

 the cover. The stones are then to be made 

 level at the top, and either covered with the 

 sod which, on breaking the ground of the 

 drain, had been laid aside for that purpose, or 

 with a covering of straw, heath, or the like. 

 This covering is to prevent the loose eartJi 

 from falling amongst the stones. 



When these operations are completed, the 

 earth which had been thrown out of the trench 

 is shovelled upon the stones until it be above 

 tlie level of the surflice. The purpose of rais- 

 ing it higher than tlie surface is to provide 

 for the subsidence of the loose earth, which is 

 generally found to be rendered more compact, 

 aud to occupy a smaller space than it did in 



its original state. When a portion of the 

 earth is shovelled in, it is an economy of labor 

 to employ a common plough for filling in the 

 remainder. 



A drain thus formed will appear on a trans- 

 verse section, as in Fig. 54, and after the sub- 

 sidence of the earth as in Fig. .55. Where 

 the soil is very soft, it is of benefit to pave the 

 lower part of the drain with stones or slates. 

 In the whole operation of forming the trench 

 and conduit, great care is necessary in seeing 

 that all the parts of the work are executed 

 well. 



Fig. 54. Fig. 55. 



The stones used for this species of dtain 

 may be sandstone, or any of the harder stones 

 that can be obtained. But, in many cases, 

 stones are not to be obtained, in which case 

 tiles may be substituted. 



Fig. 55. 



The tiles, which are made with an arch as ia 

 the annexed figure, 56 may be formed of sepa- 

 rate pieces of about tbnrteen inches in length- 

 Flat soles are made of the same material, on 

 which tlie arched tiles are to rest. 



Tlie method of forming the drain whea 

 tiles are the material employed, may be 

 somewhat different from that adopted when 

 stones are used. 



The drain is carried 

 down as narrow as a man 

 can work, and at the bot- 

 tom an excavation is made 

 by means of a narrow- 

 mouthed spade, to fit the 

 dimensions of the tile, 

 which is then placed upon 

 its stand or sole. Above 

 this shoald be laid some 

 loose materials^ as clean 

 gravel or sand, for allow- 

 ing the filtration of the 

 water. Evtn brushwood » 

 and such materials, may j. _ ^^^ 



