166 WEIGHT OF EARTH CHAP. IIL 



square foot, in a place abounding with worms, 

 on the summit of a bank, where no castings 

 could have rolled down from above. These 

 castings must have been ejected, as he judged 

 from their appearance in reference to the 

 rainy and dry periods near Nice, within the 

 previous five or six months ; they weighed 

 9|oz., or 5 Ib. 5^oz. per square yard. After 

 an interval of four months, Dr. King collected 

 all the castings subsequently ejected on the 

 same square foot of surface, and they weighed 

 2J oz., or 1 Ib. 6^ oz. per square yard. 

 Therefore within about ten months, or we 

 will say for safety's sake within a year, 12 oz. 

 of castings were thrown up on this one 

 square foot, or 6*75 pounds on the square 

 yard ; and this would give 14*58 tons per 

 acre. 



In a field at the bottom of a valley in the 

 chalk (see No. 2 in the foregoing table), a 

 square yard was measured at a spot where 

 very large castings abounded ; they appeared, 

 however, almost equally numerous in a few 

 other places. These castings, which retained 

 perfectly their vermiform shape, were col- 

 lected ; and they weighed when partially 

 dried, 1 Ib. 13J oz. This field had been 



