During the autumn following the extraordinary summer of 1865, and in which the Cattle Plague appeared, there was a very marked preponderance of insect life as compared with ordinary seasons. It is asserted by Mr Mc Dougall, of Manchester, that no case of this plague is known to have occurred where his disinfectant, which arrests decomposition, had been freely applied to and about the cattle. [ED.] And there is truth in this. It is quite certain that such atmospheric changes do take place, and prepare the way for pestilence. It is quite certain that there is an epidemic meteorology. This epidemic condition of the atmosphere is at length coming within the range of science. The first step towards this result, which promises to be of the highest practical value, we owe to the well-devised and patient observations of Mr Glashier, continued through the three recent Cholera epidemics. Among other important facts, he has determined that there is—1. An increased pressure of the atmosphere, greatest at the worst period of the epidemic. 2. An increased density of the atmosphere, not arising from an increase of watery vapour; for, 3. The quantity of water in the air was 1/20th less than the average, at the same time that the mean weight of a cubic foot of air was 2 grains above the average. 4. An unusual alternation of heat and cold, yet the heat predominating to such an extent that in particular localities it rose as much as from 2° to 8° above the average. These excesses were most striking at night, particularly in the parts of London on a level with the Thames, where the night temperatures ranged from 7°, 8°, 9°, and 10° above the temperature of the country, and even of the suburban districts. These temperatures were highest, especially the night ones, when the mortality was greatest; and the mortality was greatest where the temperatures were highest. 5. A remarkable increase above the average in the temperature of the water of the Thames. From a long series of observations it had been found that the normal temperature of the Thames is 51.7°. During the prevalence of the epidemic it rose to 60°, 66°, and once to 70°. At this temperature the “simmering” water must have poured enormous quantities of vapour into the surrounding atmosphere; not the pure vapour of water, for that cannot arise from a river which is the recipient of the foul contents of all the sewers and cesspools of the metropolis. In some instances there was an excess of 20° of the temperature of the water above that of the air. For twenty-eight continuous nights during the height of the epidemic, the average excess exceeded 16.5°. 6. An unusual prevalence of haze, mist, and fog; the fog being sometimes so dense that London could not be discerned from Greenwich.