CULTIVATION OF WHEAT 71 



of branches of the mountain-birch, fixed together with wooden 

 pegs, with tines of the tough broom." 1 The oldest and simplest 

 form of the harrow had a wooden frame with teeth of wood or 

 iron. As it was drawn over the field, it combed or raked the 

 surface quite level. Two improvements have since been made. 

 It is constructed in two or more sections so that it can accom- 

 modate itself to uneven ground; and flexible steel bars are 

 used in the frame so that by means of a lever the teeth can be 

 set at any angle. Harrows 25 feet in width are now used on 

 the large western farms of the United States. With such a 

 harrow one man and four horses can cover 60 to 75 acres per 

 day. 



Various other forms of harrows have been devised. The 

 principal ones are the spring tooth and the disc harrows. The 

 latter consists of a main frame to which are pivoted two sup- 

 plementary frames. Mounted within each one of these is a 

 shaft carrying a series of concavo-convex discs, and the whole 

 series is rolled over the ground. Adjusting levers swing the 

 supplemental frames to any angle in relation to the line of 

 draft. The soil is cut and thrown out in a degree proportional 

 to the angle set. It was first used by the Japanese in ancient 

 times. In the last decade the disc principle has been widely 

 applied to harrows, plows and cultivators. 



Cultivation by one Operation. As early as 1618 a machine, 

 worked by steam, was invented and patented in England which 

 plowed and fertilized the land and sowed the seed, all at one 

 operation. 2 There is no record of its having done any work. 

 In the same country a "double-hoppered drill-plough " was ad- 

 vertised as a new machine in 1744. It drilled and covered 

 wheat and fertilizer together. Perhaps the only instance where 

 any practical and extensive results in this line have been ob- 

 tained is in California and northwestern Canada. Gang plows 

 are used, and a broadcast seeder attached to the rear of the 

 plow sows the seed as fast as the ground is plowed. The seeder 

 is usually followed by a harrow, also attached to the plow. A 

 small outfit, operated by one man and drawn by a team of eight 

 mules, will plow, sow and harrow-in the seed in one operation 

 at the rate of from 10 to 15 acres per day. On the large farms 



1 Grey, Agr. in Northmmb., p. 4. 



1 Perels, Bedeutung des Machinenwesens, etc., pp. 11-13. 



