Since the rate of seeding any oats with a grain drill will vary considerably with the degree of cleanness of the oats, the most satisfactory method of determining an accurate drill setting for any particular lot of seed is by a calibration test. To make this test, raise and block up one side of the drill so that the wheel on that side will turn freely. The seed dropped by a certain number of revolutions of the wheel should be collected in cans, paper sacks, or on a canvas spread beneath all drill tubes. The table shows the number of wheel revolutions for various drill widths and wheel diameters to cover 1/10 acre.