Being the third of a se~~iw of lectures au .J.1Ieteorology in relation to Hygiene. I pril .~rd, 1891. IN dealing with the subject of barometrical conditions, and air' movements as related thereto, before my present audience, I feel some slight difliculty, as it is not at first sight easy to see how either the barometrical pressure or the wind llas any direct sanitary effect, except as, in the case of the former, by influencing the tidal level, and thereby river drainage, or as in the case of

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... latter, b3occasionally bringing to us odours, not of Araby the Blest, when the wind comes to us from certain definite quarters. The lecture naturally divides itself into two sections: the-Pressure and the Wind, and I shall take them in the sequence in which I have named them. Pressure I shall deal with, firstly, as to its periodical and Its non-periodical changes; and secondly, as to its physiological effects and the modes of counteracting them.