It must also be remembered, as has been pointed out before, that the success of any method of applying sewage to soil depends upon the frequent change from bed to bed, the actual time interval depending on the character of the soil. If the soil is fine, the same area may be used for a week at a time, and then given two weeks’ rest. If the soil is more open, this interval should be reduced, and with very coarse particles it may be found desirable to shift the flow from one bed to another after an interval of a few hours only. Experience and careful observation on the moisture-carrying capacity of the bed is the best guide to the operation of sewage irrigation. Whether or not this method of disposing of the sewage of a single house is to be selected depends largely upon the slope of the ground from the house toward the garden. It is not desirable to have sewage exposed to the air in the immediate vicinity of a dwelling-house. Rarely would any odors be generated to such an extent as to be offensive to the occupants of the house, since the sewage sinks into the ground before putrefaction of the organic matter sets in and the exposed material left on the surface of the ground is of too attenuated a type to become offensive even if it does putrefy before drying. There is, however, the danger of odors being formed where distribution is imperfect and where pools are allowed to form in the furrow. There is also the danger of the transmission of disease germs from the sewage-irrigated field to the occupants of the house through the agency of flies. Health statistics of English farms show this danger to be a very remote one, since the health of the workman on those farms is as good or better than the average throughout England. But the possibility of infection exists and must not be overlooked.