A wet hold diffuses moist vapour all over the ship; and it was a rule with some of those commanders whom I observed to be most successful in preserving the health of their men, not only to have daily fires in the well, but to bail out the water when the pumps could not exhaust it all, and never to allow it to collect to more than the depth of a few inches. It is, therefore, very doubtful whether it is a good practice to let in water, as is very commonly done in order to sweeten the hold, for the same sweetness will be preserved if it is kept strictly dry. If it should happen, indeed, that there should be a great deal of putrid matter in the lower parts of the ship, from previous neglect or unavoidable leakage, it may be adviseable to let in a quantity of water in order to loosen and wash off what is offensive, and then to pump it out. There is a circumstance in the first fitting out of a ship well worth attention, as highly conducive to the dryness and cleanness of the hold. I mean the choice of the ballast; for that which is called _shingle_, consisting all of pebbles, is far preferable to that which is sandy and earthy, as it does not so readily soak and retain the moisture and filth. Water or fluid of any kind readily subsides in it, and should any putrid matter be entangled in it, there will be less difficulty in washing it out. The decks should not be washed so often when the weather is moist as when it is fine, as it will be more difficult to dry them, and more harm may arise from the moisture than benefit from the cleanness. Washing should also be performed very early in the morning, even in the best weather, in order that there may be time for the decks to become dry in the course of the day. It is after a general washing that the moveable fires, formerly described, are most proper and useful. Every contrivance should be fallen upon to change the air in the orlop and hold. Ventilators and windsails[59] are well adapted for this purpose, and should be used as frequently and for as long a time as possible. It has also a good effect in cooling the air in the lower parts of a ship in the West Indies, to lift the gratings of the hatches, raising them on their edges, and lashing them to the staunchions. It contributes likewise to cleanliness and coolness to keep the decks as clear as possible from[60] chests and other lumber, which are in the way of sweeping and washing, and prevent also the free course of the air.