Among the several means of sweetening or renewing the air, we should expect to hear of Dr. Hales's _Ventilator_. I must confess it was my expectation, and therefore, persuaded as I was of the excellence of the invention, it was not without much regret that I saw so good an opportunity lost, of giving the same favourable impression of it to the Public. If a degree of success, exceeding our most sanguine hopes, is not sufficient for justifying the omission of a measure, deemed one of the most essential for attaining an end, I would plead in favour of our worthy brother, that by a humiliating fatality, so often accompanying the most useful discoveries, the credit of this ventilator is yet far from being firmly established in the navy. What wonder then, if Captain Cook being so much otherwise taken up, should not have had time to examine it, and therefore avoided the encumbering his ship with an apparatus, he had possibly never seen used, and of which he had at best received but a doubtful character? Nor was he altogether unprovided with a machine for ventilation. He had the _Wind-Sails_, though he hath not mentioned them in his Paper, and he told me that he had found them at times very serviceable, and particularly between the Tropics. They have the merit of taking up little room, they require no labour in working, and the contrivance is so simple that they can sail in no hands. But their powers are small in comparison with those of the ventilator; they cannot be put up in hard gales of wind, and they are of no efficacy in dead calms, when a refreshment of the air is most wanted. Should there be any objection to the employing both? Such were the measures taken by our sagacious Navigator for procuring a purity of air. It remains only to see in what manner he supplied pure water; another article of so great moment, that the thirsty voyager, upon his salt and putrid diet, with a short allowance of this element, and that in a corrupted Rate, must account a plentiful provision of fresh water to be indeed the _best of things_.