A recent report on yellow fever states the interestiug fact that this disease never occurs in any climate at the height of 2,500, feet. It has never happened in the United States at an altitude of over 460 feet, which point it reached only in Arkansas. In the Island of Dominica it has been observed that, at an eminence of not more than 1,500 feet, it is always healthy, however tho epidemie may rage in the lowionds. It is concluded by medica] men that tho etratum of air infected by the poison is heavier than pure atmosphere, and therefore sinks. Henee, they recommend that, in unhealthy districts, house s and hospitals shoulc be situated above the fever stratum " here hills are accessible, patients should be carried to a height of a least 500 feet.