OPEN DRAINS. 175 



class of work is unquestioned. By means of them, 

 large and deep ditches such as are required to drain 

 from 2000 to 40,000 acres of level land can be profitably- 

 excavated. 



The machines are above described to indicate the two 

 general methods of working which are successfully 

 used rather than to particularize machines. 



Ditching with Teams. 



Ditching with teams can be done profitably only 

 under favorable conditions of earth and weather. 

 Teams can be worked only where the animals can ob- 

 tain a secure footing. The excavation is done with 

 steel scrapers or ^^ slips" after the earth has been 

 loosened with the plough. Clay that contains a small 

 per cent of sand will cut and dump with ease, while 

 heavy clays of all kinds are exceedingly tough when 

 found in their natural places in lands requiring ditches. 

 However, the soil and subsoils are so various in differ- 

 ent locaHties that nothing more can be said than that 

 where this method is used every advantage of soil, 

 season, and weather must be taken or the work may 

 be blocked and laid over until the next favorable time. 

 Road-graders with carriers for depositing the earth 

 clear of the ditch-banks may be used where the earth 

 will plough well and there is abundant room for operat- 

 ing. They require twelve horses and three men and 

 will make a ditch about 2 feet deep with side slopes 

 of 2 to I or more, except for large canals, where they 

 can be used to advantage for any depth and width. 



With reference to laying out and testing ditches 

 which are made by teams it should be observed that 



