346 REMOVING OYERLAf; 



where the overlay was dry and sandy, but also lower down in the 

 wet springy gravel, often indurated by ferruginous cement; and 

 even to some extent, in the wet, miry, and sticky clay still lower. 

 Difficult as was this lowest part of the uncovering, in every mode, 

 the scraper took up the clay, and let it drop because of the weight 

 of the mass, much better than any hand utensils. In this, the 

 plough was not needed, nor could the scraper be used much, because 

 the feet of the horses sank through both the miry clay and the 

 upper thin layer of soft marl (Fig. I.), and would have worked up 

 both together. 



But the plough and scraper could not serve for all the overlay. 

 Not only for the miry clay layer, but for much of the other over- 

 lay, either because of its texture, or its place, it was still cheapest 

 to remove by hand implements, as previously; and especially for 

 giving the final shaping to the opening. If the job had been con- 

 tinuous and regular, and the labourers all able men, it would pro- 

 bably have been cheaper to remove the whole overlay at once in 

 wheel-barrows, in the manner of excavating for canals and railroads. 

 As it was executed, the saving of labour in removing the overlay 

 was fully one-half of the former cost. 



To return to my actual labours. As soon as the wet gravel 

 (Fig. I.) was laid naked, the land-side outline of the range was 

 marked off, and a narrow ditch (c, d, e, e, x, Fig. II.) dug along 

 it down to the marl, intercepting the numerous small springs, and 

 conveying the water into the stream (at e, x, Fig. II.). After re 

 maining thus drained for some weeks, the clay, though still miry 

 and sticky, is worked much more easily ; and in later operations, 

 has been mostly removed in carts, which were drawn upon the then 

 partly excavated and firm marl. The scrapers' work had pre- 

 viously served to fill the sinks and pools in the older ranges, with 

 dry sand and gravel ; forming a drained, firm, and nearly level sur- 

 face, on which the carts carried and dropped the remaining clay 

 overlay. 



The design of the plan of operations was to have the carts to 

 descend upon the marl, and to draw loads ultimately from the 

 lowest digging. For this purpose, as has been stated, part of the 

 overlay had been left on the upper end of the range (a, m, o, Fig- 

 III.), forming a sloping roadway for 96 feet of length, and rising 

 5 feet in that distance, from the marl to the road on the surface 

 of the land. A few yards of " poling" over the soft clay bottom 

 layer served to make a firm passage from the marl to the dry 

 Handy earth. The marl, except its upper 6 inches, was at first 

 firm enough for the loaded carts; and soon became dryer and firmer 

 in drying. The slope, given by the digging and removal of the 

 marl, descending always to one side and to the lower end, where 

 there was a discharging outlet into the stream for all water, 



