290 WORKING WET MARL PITS. 



so that the digging shall be the lowest around the outside, and 

 gradually rise in level to the middle of the area ; or next to the 

 old diggings, now heaped with the later removed overlay. What- 

 ever water may find its way within the work, whether from oozing, 

 rain, or accidental bursting of the little surface drain, will run to 

 the outside, the dip of which should lead to the lower main drain. 

 After this form has once been given to the surface of the area, 

 very little attention is required to preserve it j for if the successive 

 courses are dug of equal depth from side to side, the previous- 

 shape will not be altered. The sides or walls of the pit should be 

 cut (in descending), something without the perpendicular, so that 

 the pit is made 12 or 15 inches wider at bottom than top. The usual 

 firm texture of marl will prevent any danger from this overhanging 

 shape, and several advantages will be gained from it. It gives more 

 space for work prevents the wheels running on the lowest and 

 wettest parts allows more earth to be disposed of, in opening for 

 the next pit and prevents that earth from tumbling as easily into 

 the next digging, when the separating wall of marl is afterwards 

 cut away. The upper and larger drain of the pit, which takes the 

 surface water, will hang over the small one below, kept for the 

 oozing water. The former remains unaltered throughout the job r 

 and may still convey the stream when six feet above the heads of 

 the labourers in the pit. " The lower drain of course sinks with the 

 digging. Should the pit be dug deeper than the level of the main, 

 receiving ditch can be sunk, a wall should be left between, and the 

 remainder of the oozing water must be conducted to a little basin 

 near the wall, and thence be bailed or pumped into the receiving 

 ditch. The passage for the carts to ascend from the pit should be 

 kept on a suitable slope ; and the marl forming that slope may be 

 cut out in small pits, after all the other digging has been completed. 



If the marl is so situated that carts cannot be driven as low as 

 the bottom, either because of the danger of flooding, or that the 

 ascent would be too steep for sufficiently easy draught, then the 

 area must be cut out in small pits, as before stated, beginning at 

 the back part, and extending as they proceed, towards the road 

 leading out of the pit. 



It is the less required to extend directions for the mode of work- 

 ing low-lying marl, covered and sourrounded by higher land, and 

 by its springs, because large excavations under these difficulties, 

 will be described in a later part of this work, and the w^ole course 

 of procedure minutely stated. 



In some cases, either because of the great liability of the over- 

 lying oozy earth to crve and fall in, and thus continually to choke 

 the surrounding marl drains, or of rain-floods to fill and damage 

 the excavations, it is too hazardous to leave diggings unfinished for 

 any length of time ; and still more for the unfinished work to be 



