SPRAY PUMPS.--The application of the foregoing spray mixtures is fully as important as the sprays themselves, for on the right application at the right time depends the efficacy of the spray. For this purpose a considerable amount of special machinery has been devised. Lack of space prevents us from going into much detail on this question, so we must be content with merely outlining the different types of machines and mentioning their accessories. Sprays are forced through single, double or triple acting pumps, either by hand or power. The three types of power available are traction, compressed air, and gasoline, the last being the most used. Steam power is practically obsolete. The knapsack is the simplest type of hand pump, but it is of no practical use in the mature apple orchard. For small orchards and small trees several types of hand pumps are quite effective. The lever type of pump, where the handle is pushed from and pulled toward the operator, probably gives the most power with the least tiring effect, because it enables one to use the weight of the body to some extent. It is best not to have the pump attached to the spray barrel or tank, but set on a movable base of its own, as then it can be used for any one of a number of barrels. Such an outfit may be obtained for from twenty-five to forty dollars. It is well to buy a standard make of pump, preferably from a nearby dealer, so that repairs may be readily secured. For all orchards up to three or four acres in size, and for larger orchards where the trees are not over twelve or fifteen feet in height, this kind of spray rig is the most practicable and advisable, when the expense is taken into consideration. This applies especially to the general farm. The power of a traction sprayer is developed from the wheels. There is much discussion as to whether sufficient power to throw an effective spray can be supplied by this method. By accumulating considerable pressure by extra driving at the ends of the rows and then skipping every other tree in order to keep up the pressure, going over the rows twice, a very satisfactory pressure can be obtained for trees which are not too large. The argument for this type of machine, and it is especially applicable on the general farm, is that it can be used for other spraying on the farm as well as for the apple orchard, especially for potatoes and small fruits. It is a comparatively cheap type of power, particularly when it can be used for several purposes.