30 BULLETIN 1447, U. S. DEPARTMENT OF AGRICULTURE 
In general, it may be said that the operations on which the tractor 
was most generally used (plowing, disking before plowing, and har- 
vesting with the combine) are operations which replaced a large 
number of horses and at the same time saved man labor. 
TYPES OF COMBINES 
_ As classified herein, motor-driven combines are those that have 
an engine installed on the machine to operate the mechanism of the 
separator and are drawn over the ground either with horse or tractor 
power. Ground-power combines derive their power for operating 
the mechanism of the separator from the traction of the wheels, as 
the machine is drawn over the ground. The quality of the work 
done by ground-power combines is generally considered to be inferior 
to that of motor-driven machines, and the ground-power type is fast 
becoming obsolete. Table 26 gives the number of each type of com- 
bine on the farms studied, classified by size (length of cutter bar). 
Hereafter no reference will be made to the ground-power type, all 
figures and discussion dealing exclusively with the more important 
type—the motor-driven combine. 
TABLE 26.—Number of motor-driven and ground-power combines, by sizes, 
1920-1922 
: _| Percentage of total number of 
: Contbines combines 
Type and size 
(Length of cutter bar, feet) i 
1920 1921 1922 1920 1921 1922 
Motor-driven type: Number | Number | Number | Per cent | Per cent | Per cent 
Obert BSE MENS | Soa dan Se poe, Se ken eo 23 22 21 26 
NDE to ee OS a age ee ee 12 16 15 17 19 19 
1 So rep oe aati CY ea tee eee. SOY 3 6 7 4 7 9 
DIG pes 8 ea re See Sms She hp oe ae PT es og 5 a 4 uf 9 5 
Si Ses Ae Bee Se I ieee 12 14 15 17 N¢/ 19 
XD) yea pic ee Slinae so pel ye axe tire Me cer ey? Le 13 13 14 18 16 17 
rN fas 5 Se 2 Nea RP My Me al 1 1 it 1 1 1 
74: 1S ae ee aE OS BE Res Re Re ie Seder 15 3 3 3 4 4 4 
AN OLAS es ak ere Sane Ue eee See 12 82 80 100 100 100 
Ground-power type: 
ie he TB & ot : RARE ee eh SIA eee 19 16 15 70 62 66 
17 {ay Ses aN nN ie PIE sap mani’ ohRS re TUR ad oo 8's 4 4 3 15 15 13 
LS se ESP PS a ere Ae Op mee 4 4 3 15 15 13 
TU 3a cae RIN eh Ye tbl iH | Me a 1 1 Wes pet le aa 4 4 
Se ok = ath Pa ae ST a I pg Ce Ga | A ek ch 1 1b Le ee oe aan 4 4 
Motalic2 22s Sie BON Sarees hes eee ias 27 26 23 100 100 100 
CHOICE OF COMBINE WITH REFERENCE TO SIZE 
The size of combine now owned, the percentage of owners who 
would buy another combine when the present one is worn out or 
becomes obsolete, and the size recommended if another was bought 
is shown in Table 27. All but two owners stated that they would 
buy another combine when needed. Of the total number recommend- 
ing the purchase of another combine, about 30 per cent recommended 
the 12-foot and 21 per cent recommended the 18-foot combine. 
