letween Rotherhithe and Limehouse. 379 



At 992 feet, Clay and shells ....... O 8 



Sand 4 4 



5 



At 1011 feet, Sand 3 6 



Clay 1 6 



5 O 



The quantity of water in the gravelly stratum No. 2 of 

 the shaft, was so considerable, that a fourteen-horse engine 

 could only keep the water a few feet below its natural level, 

 and the shaft was sunk through, by far the greatest part of 

 this stratum, into the blue stratum No. 3, with the water 

 standing in it to the depth of several feet. It is well ascer- 

 tained that this stratum of gravel extends through a consi- 

 derable part of the adjoining country; but borings being 

 made in the shaft from the bottom of this stratum, no wa- 

 ter was met with in the sub-strata to the depth of eighty-six 

 feet from high water, where a spring was discovered, which 

 rose in a few hours, through pipes inserted for that purpose, 

 to a higher level than that in the gravelly stratum No. 2, 

 The shaft was therefore sunk only to the depth of seventy-six 

 feet four inches. 



The drift was then carried forward in a horizontal direc* 

 tion to the north, five hundred and fifty-nine feet. And, in 

 order to explore the ground in the northern part of the line 

 of the then proposed tunnel, the drift was turned to the 

 west twenty-three feet six inches from the centre of the 

 former line to the centre of the new direction, and then to 

 the north, as shown in Fig. 2, (intended to be enlarged af- 

 terwards to the size of the tunnel) and carried forward three 

 hundred and forty-one feet, making the distance from the 

 shaft to the beginning of the rise at D nine hundred and 

 twenty-two feet. Through the whole, of this line no ma- 

 terial interruption occurred ; the strata, as shown above, 

 consisted of firm sand, calcareous rock, and concreted tra- 

 vel, with no more water than was easily kept under by a 

 fourteen-hovse engine. 



At the point D the drift was made to incline upwards at 

 the rate of one foot in nine. In prosecuting this part of the 

 drift, at the distance of. twenty-three feet from the begin- 

 ning of the incline, the earth in the roof broke down, and 



discharged 



