It is not always advisable to stop picking when the heat becomes too great. A better method is to stack the trays in the field, so as to protect the raisins from the sun. When the heat subsides, the trays are again spread. The expense and trouble of stacking the trays is not as great as may be supposed, and a few hours will generally suffice to stack a large vineyard with the regular picking gang. Some packers have suggested that to secure good raisins the trays should be stacked for several weeks in the beginning of the period of drying. For the production of our usual dark-colored raisins this is not necessary nor even advisable, except when the heat is such that the raisins would cook and spoil. With a little experience this cooking of the grapes can be readily detected by the smell emitted by the grapes. As soon as they are in the least injured by the heat, a cooked flavor begins to pervade the whole vineyard. When this peculiar flavor is noticed, and when the berries begin to show small red and soft blotches on the side facing the afternoon sun, the stacking should be commenced as quickly as possible. If the trays are kept in piles for several days, the injured grapes will partially recover and at least to some extent regain their color. Greatly injured grapes will dry much slower, sometimes remaining several weeks behind those which were not injured by the sun. Slightly discolored raisins may partially regain their color by sweating, but they will not improve otherwise. After the trays are filled with grapes, the best way is to put several rows of trays together, or rather to place the trays from three rows of vines along one of the spaces between the rows. This gives more compactness to the crop, makes it easier to handle the trays, and facilitates the stacking of the trays, their turning and reversing, or any labor with the trays that may be required. By thus clearing some of the spaces between the rows, admission for trucks and wagons is had close to the trays.