The cost of plowing with a traction engine depends upon so many factors that it is difficult to make any definite statement. It depends upon the condition of the ground, size of the tractor, the number of plows pulled, and the amount of fuel used. An 8-16 horsepower tractor, for instance, burning from 15 to 20 gallons of low grade kerosene per ten hour day and using one gallon of lubricating oil, costs about $1.90 per ten hours work. Pulling two 14-inch plows and traveling 20 miles per day, the tractor will plow 5.6 acres at a fuel and an oil cost of about 30 cents per acre. Pulling three 14-inch plows, it will turn 8.4 acres at a cost for fuel and oil of about 20 cents an acre. The kind and condition of soil is an important factor in determining the tractor cost of plowing. Comparison between the average horse cost and the average tractor cost suggests very interesting possibilities in favor of tractor plowing under good management. Aside from the actual cost in dollars we should also remember that no horse gang can possibly do the quality of work that can be accomplished by an engine gang. Anxiety to spare the team has cut a big slice off the profits of many a farmer. He has often plowed late on account of hard ground, and he has many times allowed a field to remain unplowed on account of worn-out teams. Under normal conditions, late plowing never produces as good results as early plowing. Many a farmer has fed and harnessed by the light of the lantern, gone to the field and worked his team hard to take advantage of the cool of the morning. With the approach of the hot hours of midday, the vicious flies sapping the vitality from his faithful team, he has eased up on the work or quit the job. In using the tractor for plowing, there are none of these distressing conditions to be taken into consideration, nothing to think of but the quality of work done. It is possible to plow deep without thought of the added burden. Deep plowing may or may not be advisable. But where the soil will stand it, deep plowing at the proper time of year, and when done with judgment, holds moisture better and provides more plant food. The pull power required to plow different soils varies from about three pounds per square inch of furrow for light sand up to twenty pounds per square inch of furrow for gumbo. The draft of a plow is generally figured from clover sod, which averages about seven pounds per square inch. Suppose a plow rig has two 14-inch bottoms, and the depth to be plowed is six inches. A cross section of each plow is therefore 14 by 6 inches, or 84 square inches. Twice this for two bottoms is 168 square inches. Since, in sandy soil, the pressure per square inch is three pounds, therefore 168 times 3 pounds equals 504 pounds, the draft in sandy soil. 168 times 7 pounds equals 1,176 pounds, the draft in clover sod. 168 times 8 pounds equals 1,344 pounds, the draft in clay sod.