I30 



Charles Darwin. 



cember, 1842, Darwin, waiting twenty-nine years, 

 or until November, 1871, before noting the results ; 

 a trench was then dug across the field exposing a 

 series of white dots or nodules ; the original deposit 

 of chalk being found on both sides of the trench at 

 a depth of seven inches from the surface. Another 

 portion of this field was spread with cinders in 1842, 

 and twenty-nine years later the stratum was also 

 found seven inches below the surface, so that Dar- 

 win assumed that the mould, exclusive of the turf, 

 had been thrown up at an average rate of .22 inches 

 per year. 



These and other experiments resulted in the 

 work, " Formation of Vegetable Mould," published 

 in 1882. All experiments were carried on in the 

 same methodical manner, exactness, conclusiveness, 

 and simplicity being the characteristics of all the 

 work of the great naturalist. 



