It is a very salutary practice to let down fires frequently into the well, both in order to purify the air and to dry the surrounding parts. It was formerly mentioned that this was daily done in the Intrepid, and the effect of it was to remove the wetness of the ballast and the mouldiness which had overspread the sides and beams; and having had the effect of sweetening and purifying the air, it seemed to be the principal circumstance that tended to make this ship extremely healthy from being the most sickly of all the fleet. This precaution, as well as every other point of cleanliness, is more necessary in large ships, because the mass of foul air, as well as the quantity of corrupting materials, is greater[58]. The following fact strongly evinces the good effect of fire and smoke:--When it was the custom for frigates to have their kitchens between decks, they were much more healthy than in the present construction, in which they have them under the forecastle, where the heat and smoke are dissipated without being diffused through the ship, and causing a draught of air upwards, as formerly. The men derived then also great benefit and comfort from having a large fire, round which they might assemble to warm and dry themselves in a sheltered place. I leave it to those who preside in the construction of the navy to determine how far it would be advisable to return to the old manner of construction. The French ships of the line have their kitchens and ovens between decks, and this must tend to counteract the effects of their want of cleanliness. The Dutch ships of the line have their kitchens on the orlop deck, which must be still more conducive to the general purity of the air. Moisture is pernicious both in itself and as the instrument of putrefaction. All the complaints, called colds, are more owing to wet than cold; and moisture may be the means of producing, or at least of exciting dangerous fevers, when they would not otherwise appear. It besides contributes greatly to the production of scurvy. Ships built of ill-seasoned wood are found to be very unhealthy on account of the moisture contained in it. The moisture of timber arises not only from being used too soon after being felled, but also, as I am informed, from being stripped of its bark and outer surface when piled and exposed to the weather in dock yards. This method of smoothing and piling the wood is only a late practice; and the advantage in point of convenience and neatness seems to be more than overbalanced by the detriment it thereby receives.