ON LANDSLIPS. 313 



it first came clown. This old top soil rests upon 5 or 6 feet 

 of oolitic debris overlying the white oolitic rock, as is usual 

 in those parts having a rock subsoil ; but, upon this old top 

 soil, there was a coating of about six inches of the fuUer's- 

 earth clay under the "slipping surface," on which the slip 

 moved downwards. The clay during excavation always 

 broke away from and exposed the smooth and polished 

 " slipping surface," which, in this case, was highly and 

 strangely coloured with green, orange, and purple in stripes, 

 showing the direction of the slip. These prismatic colours 

 were the admiration of the navvies, and I put away a fine 

 sample, but lost it on removal. 



Before the railway was begun this slip had apparently 

 come nearly to an equilibrium, for it was only perceived to 

 move a very little during wet times. But after the railway 

 had been made the condition of things was quite altered, 

 and I pointed out to Brunei what I took to be the state of 

 things then / namely, that the railway, by cutting through 

 the neck of the slip, had altogether removed from it the 

 buttress formed by the large lower mass, and that I was sure 

 the slip would again advance, and with more rapidity, and 

 thus endanger the railway. I accordingly proposed to him 

 to drain the upper parts of the slip by a heading drain, at 

 a cost of about £750 ; but he would not go to the expense. 



The line was opened shortly afterwards, and then I went 

 to take charge of the Hereford, Ross, and Gloucester line ; 

 but just when I wxnt there had been some heavy rains, 

 which set the slip moving again. It came down suddenl}- 

 and with great pressure against the small portion of it 

 which had been left under the railway. This small re- 

 mainder could not shove forward the heavy lower mass on 

 which the house had been built, so it squeezed up the part 

 under the railway, as I had anticipated, and raised up the 



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