Of Impure Air. "The vital air "Pervades the swarming seas, and heaving earth, DARWIN. THE absolute necessity of animals breathing pure air, in order to enjoy good health, has been admitted, even by those who entertain opposite opinions on almost every other subject. Even food itself is of less importance to warm blooded animals than pure atmospheric air. The one, we only require at stated periods, but our demand for the other is continual, during the whole of our existence. Happily for man, he has not to depend on his own industry, nor the caprice of others, for his atmospherical supply, otherwise his preservation would have been in continual danger. But the great and bountiful Author of Nature has secured us against such a risque, by the universal diffusion of atmospheric air over all habitable space. Yet, although we are liberally supplied, so far as regards quantity, we are frequently doomed to suffer from aerial changes, and its occasional insalutary impregnations.* But, as atmospherical mutabilities arise from causes we are seldom able to counteract, they are only to be guarded against by suitable clothing. Impurities of the air are sometimes more within our range of action, being frequently generated by known causes, as putrid marhes, filth in a ship's hold, &c. and this leads me to consider its bad effects on those exposed to its influence. It has been calculated, that the internal surface of the lungs of a man of common size, measures upwards of 21,000 square inches. It is evident, when this extensive surface comes in contact with air, loaded with moisture or charged with pestilential gases, disease must be generated in the latter instance, and heat abstracted in the former; owing to water being a most powerful conductor of caloric. Besides, air, thus saturated by humidity, is incapable of giving a due degree of excitement * This seems to be in unison with the great divine plan; something is generally left us to perform, and it is only in making such attempts, that talent is developed, and discoveries made. to the circulation, consequently, digestion, and all the secretions and excretions become impaired. It is furthermore certain, that moist air is lighter, and contains less of the vital stimulus, than dry air; hence, it follows, that the heat of the body is reduced two ways; first, by moisture, and secondly, by a deficiency of oxygen in the atmosphere, the source of animal heat. Of Wind-sails and Stoves. THE popular system of washing the lower deck would be less lamentable, if its effects were only temporary, or if we possessed the means of counteracting its baneful influence. But hitherto we know of no remedy which has the least claim to being even generally useful, and thus a strong disposition to disease is planted, with the most limited means of removing it. Wind-sails and stoves are the means resorted to at present, for drying and ventilating a British man of war; and they may very properly be nominated a remedium miserabile. In ships where wind-sails are put down every morning, after the manner of other routine duty, and suffered to remain, though rain or strong wind should supervene, they are often produc F tive of much harm, by being a medium for the introduction of moisture and strong wind into the lower deck. In fact, wind-sails cannot be used at all, (at least with advantage,) either during the presence of strong wind, rain, calm weather; and seldom when the ship is under way. When air is introduced into the lower deck, through the medium of these canvas conductors, they, of necessity, end abruptly near some of the men's berths, and if the wind should happen to be at all strong at the time, the current of air will be such, as to be very hurtful to those who sit in the vicinity of their termination. Again, during the continuation of fair weather, with gentle breezes, (when they are least wanted) windsails will have a salutary tendency, if carefully trimmed and shifted. But whenever the wind is strong, the termination of the windsail should be directed from the men's berths towards the ceiling of the deck, by means of an elbow, to be attached and detached at pleasure, as recommended by the Right Hon. Sir John Sinclair, Bart.* During the period I belonged to the Royal Squadron, on His Majesty's visit to Scotland, the Right Honorable Sir John Sinclair, Bart. did me the honor to give me a plan explanatory of his "Improved Mode of ventilating Thus it appears, from what has been observed, that there are many circumstances which render the operation of windsails uncertain, negative, or detrimental; and that, on the whole, they are far from being a remedy against moisture. STOVES are not allowed to a sufficient extent in the royal navy, nor are the small number issued, often put under requisition. But, if both these defects were remedied, any number of stoves would not be capable of drying in ten hours, that which had been wetted in as many minutes. For, owing to the peculiar construction of a ship's stove, the rays of heat are totally radiated upwards, drying only the atmosphere and ceiling of the deck; leaving the lower deck in nearly its original humid state. Moreover, there is usually a sulphurous smell Houses," and, at the same time, suggested to me the propriety of attaching an elbow to the bottom of the windsail now in use in His Majesty's ships, in such a way, that the force of the current might be expended on the ceiling of the lower deck, between the beams. By such an alteration, (as the Right Honorable Bart, observed,) "the air would be more uniformly diffused, and any possibility of the bad effects of a draught totally prevented." |