170 WEIGHT OF EARTH Chap. III. 



enclosed common land, at a height of about 

 700 ft. above the sea, at some little distance 

 from Leith Hill Tower. The surface was 

 clothed with short, fine turf, and had never 

 been disturbed by the hand of man. The 

 spot selected appeared neither particularly 

 favourable nor the reverse for worms ; but I 

 have often noticed that castings are especially 

 abundant on common land, and this may, 

 perhaps, be attributed to the poorness of 

 the soil. The vegetable mould was here 

 between three and four inches in thickness. 

 As this spot was at some distance from the 

 house where the lady lived, the castings were 

 not collected at such short intervals of time 

 as those on the terrace ; consequently the 

 loss of fine earth during rainy weather must 

 have been greater in this than in the last 

 case. The castings moreover were more 

 sandy, and in collecting them during dry 

 weather they sometimes crumbled into dust, 

 and much was thus lost. Therefore it is 

 certain that the worms brought up to the 

 surface considerably more earth than that 

 which was collected. The last collection 

 was made on October 27th, 1871 ; i.e., 367 



