Book II. EXECUTION OF CANALS. 555 



3551. Puddle is not, as somo have attempted to descrilje it, a kind of thin earth mor- 

 tar, 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, 

 imtil the mass is rendered homogeneous, and so much condensed, that water afterward* 

 cannot pass through it, or but very slowly. 



3552. The best puddling stiifis rather a lightish loam, with a mixture of coarse 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 ; vege- 

 table 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 temptation 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. 



3553. That the j)rincipal operation of puddling consists in consolidating the mass, is 

 evident from the great condensation that takes place ; it is not an imcommon case, where 

 a ditch is dug, apparently in firm soil, that though great quantities of water are added 

 during the operation, yet the soil that has been dug out will not more than two-thirda 

 fill up the ditch again, when properly worked as puddle. 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 in plenty, and if it be not, it must be carefully sought for, and carefully wheeled 

 out, or reserved wherever any is found in the digging ; or, perhaps, procured at consider- 

 able distances from the line, and brought to it in carts. It has happened in some stone 

 brash or loose rocky soils, that all puddling stuff for several miles of the line, required 

 to be brought to it ; but even this expense, serious as it may be, ought not to induce the 

 copying of those, who have left miles of such banks without puddling, and have made a 

 winter canal, but 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 land- 

 owners, to require the company to cause all the banks that need it to be secured by pud- 

 dling, 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. 



3554. History of puddling. It appears that the Dutch have been in the habit of mak- 

 ing mud ditches to secure the banks of their canals and embankments, from time im- 

 memorial ; and that, operations similar to our puddling have been long known on the 

 continent, but it is not clear at what period it was introduced into this country. We 

 think that the fens in Cambridgeshire and Lincolnshire, in which so many works have at 

 different times been executed by Dutchmen, are the most likely places in which to 

 search for early evidence of its use. We cannot think that Brindley was the first who 

 ever used it in this country, although we might admit that the Bridgewater canal was 

 the first in which it was systematically used as at the present day. If we compare our 

 first, fourth, and fifth cases (3550.), we shall find in all of them a water-tight stratum, 

 as the basis ; and the practice in these cases is to make a wall of puddle, called a puddle- 

 ditch, or puddle -gutter, within the bank of the canal ; these puddle-gutters are usually 

 about three teet wide, and should enter about a foot into the water-tight stuff, on which 

 they are always to be begun : and they should be carried up as the work proceeds, 

 to the height of the top water-line, or a few inches higher. Our second and third 

 cases (3550.), evidently will not admit of the above mode, because we have no water-tight 

 stratum on which to begin a puddle-gutter, as a bottom : in tliese cases, therefore, it 

 is usual to apply a lining of puddle to the sides and bottom of the canal. 



3555. Adjustment of materials. Canals set out with the care that we have recom- 

 mended, will always have the proper quantity of stuff to allow for the settlement of the 

 banks, since the united sections of the loose banks will always equal the section of ex- 

 cavation in the same settled or consolidated state, in which it was before the digging 

 commenced. The slopes of made banks, it is to be observed, on account of their 

 settling, should be steeper in the first instance than they are ultimately required 

 to be. 



3556. The letting of the cutting of certain lengths of the canal to contractors, who 

 will employ a number of navigators under them, in digging and puddling the canal, 

 is the next business. It is usual to let the work at a certain price per cubic yard of 



