V"^ 



62 PRINCIPLES OF GARDENING. [CH. II. 



■weighing in the aggregate 17,000 cwl., or 850 tons, 

 and during the work he moves over a distance of 

 fourteen miles. As the spade weighs between eight 

 and nine pounds, he has to lift, in fact, during the 

 work, half as much more weight than that above 

 specified, or 1,278 tons. An able-bodied labourer 

 can dig ten square perches a-day. 



A four-pronged fork, with the prongs twelve 

 inches long, and the whole together forming a 

 head eight inches wide, is a more efficient tool for 

 digging than the common spade. It requires the 

 exertion of less power; breaks up the soil more 

 effectually ; and does not clog even when the soil 

 is most wet. It is less costly than the spade, and 

 when worn can be relaid at a less expense. 



The following table, being the results of the ex- 

 periments of M. Schluber, exhibits the comparative 

 labour required in digging various soils, and the 

 same soil in various states. Thus if to penetrate 

 with a spade, when dry, grey pure clay, required 

 a force represented by 100, then to penetrate an 

 arable soil in the same state would require a force 

 equal only to 33, or about one-third ; so in a wet 

 state the clay would adhere to the blade of the 

 spade with a force equal to 29.2 lbs. the square foot, 

 while the arable soil would only adhere to the same 

 surface with the force of 6.4 lbs. 



