MO PRACTICE OF AGRICULTURE. Pakt III. 



Whert thtrt is deep cutting on «»,■ tide [c), or both (rf, e), a bench or bcrm (rf, c) is provided to 

 retain and prevent the loose earth that ma) moulder down from theuppei bank from tailing into tliecanat 

 The banks are usually ma le one foot higher than the water is intended to stand in them. 



In lev, (cutting i fig, 575. a, 1> , the height of tin- canal should be to contrived, that in any cross 

 section the Sum of the areas of the made banks ,/, I, should just equal that of the area of the section of 

 excavation /). 



In side-lying ground lfig.S15. <-, and.//- 676L/), the same object mav be attained with a litt'e extra 

 calculation ; and in all other cases oj, A), tlie engineer will allow the perfection of his skill in so conducting 



576 



~a=ls\ 



the line, that rverv embankment shall have deep cutting at both, or at least at one of its ends, to furnish 

 the extra stuff with least expense in moving it; in liKe manner, every deep cutting (rf, e) should have 

 embankments at one or both of its ends, to receive the extra stuff'. 



:'S'J:5. Before cutting out the lock-spit, or small trench between the several slope holes, 

 as a guide t<> the men who are to dig, the engineer ought to cause holes to be dug in the 

 line of the canal, near every second or third level peg, or oftener, if the soil be variable, 

 in order to prove the soil to a greater depth, by two or three feet, than the cutting of the 

 canal is to extend ; and each of these the engineer ought carefully to inspect, in order 

 to determine what puddling or lining will be necessary; and what will be the diffi- 

 culties of digging, owing to the hardness of the stuff, or to water that must be pumped 

 out, &c. ; all which circumstances, as well as the extra distance that any part of the stuff 

 may require to be moved, must be well considered before the work can be let to the 

 contractors. 



3S24. The puddling or lining nf the cannl, to make it hold water, is a matter of the 

 greatest importance, and we shall consider five cases that are likely to occur or present 

 themselves in the search into the soil that is to be dug, by sinking holes as above 

 mentioned. The first case we suppose to be that in which the whole is clay, loam, or 

 other water-tight stuff; all soils that will hold water, and not let it soak or percolate 

 freely through them, are called water-tight. Our second case is that in which the 

 whole cutting will be in sand, gravel, loose or open rock, or any other matters that will 

 let water easily through them, and such are called porous soils or stuffs. The third 

 case, we suppose to have a thin stratum of water-tight stuff on the surface, and to have 

 porous stuff for a considerable depth below. The fourth case may have porous stuff near 

 the surface, and water-tight stuff* at the bottom of the canal. The fifth case is that 

 where water-tight stuff' appears on the surface ; and below this a stratum of porous stuff", 

 but having again water-tight stuff at no great distance below the intended bottom of the 

 canal. The new-raised banks are always to be considered as porous stuff, as, indeed, 

 they will always prove at first, and in a great portion of soils they would ever remain so, 

 unless either puddling or lining were applied ; all ground that has been dug or disturbed, 

 must also be considered as porous. It should also be remarked, that any kind of soil 

 which is perforated much by worms or other insects, should, in canal-digging, be consi • 

 dered as porous stuff. 



3825. Puddle is not, as some have attempted to describe it, a kind of thin earth mortar, spread on places 

 intended to be secured, and suffered to be quite dry before another coat of it is applied ; but it is a mass of 

 earth reduced to a semifluid state by working and chopping it about with a spade, while water, just in the 

 proper quantity, is applied until the mass is rendered homogeneous, and so much condensed that water 

 afterwards cannot pass through it, or but very slowly. 



382R The best puddling xftj/fis rather a lightish loam, with a mixture of course sand or fine gravel in 

 it ; very strong clay is unfit for it, on account of the great quantity of water which it will hold, and its 

 disposition to shrink and crack as this escapes ; vegetable mould, or top soil, is very improper, on account 

 of the roots and other matters liable to decay, and leave cavities in it ; but more on account of the tempt- 

 ation that these afford to worms and moles to work into it, in search of their food. Where puddling stuff 

 is not to be met with, containing a due mixture of sharp sand, or rough small gravel stones.it is not 

 Unusual to procure such to mix with the loam, to prevent moles and rats from working in it; but no stones 

 larger than about the size of musket bullets ought to be admitted. 



3837. That the principal operation of puddling consists in consolidating the mass, is evident from the 

 great condensation that takes place ; it is not an uncommon case, where a ditch is dug, apparentlj in firm 

 soil, that though great quantities of water are added during the operation, yet the soil which has been dug 

 out will not, when properly worked as puddle, fill up more than two thirds of the ditch. It should seem, 

 also, that puddle is rendered by that operation capable of holding a certain proportion of water with great 

 obstinacy, and that it is more fit to hold than transmit water. It is so far from true, that puddle ought 

 to be suffered to get quite dry, that it entirely spoils when by exposure to the air it is too much dried ; 

 and many canals which have remained unfilled with water during a summer, after their puddling or lining 

 has been done, have thereby become very leaky, owing to the cracks in the puddle-ditches or lining. One 

 of the first cares of an engineer, when beginning to cut a canal, is to discover whether good puddling stuff 

 is plentiful ; and, if it is not, it must be diligently sought for, and carefully wheeled out or reserved 

 wherever any is found in the digging ; or, perhaps, it must be procured at considerable distances from the 

 line, and brought to it in carts It has happened m some stone brash or loose rocky soils, that all puddling 

 stuff for several miles of the line required to lie brought to it; but even this expense, serious as it may be, 

 ought not to induce the imitating of those, who have left miles of such banks without puddling, and have 

 made a winter canal, but one which no stream of water that is to be procured can keep full in the summer 

 months. It is usual in canal acts to insert a clause, for the security of the landowners, to require the 

 companv to cause all the banks that need it to be secured by puddling, to prevent damage to the land 

 below by leakage ] and it would have been well for all parties, in many instances, if this clause had been 

 enforced. 



