During the period when the infection did spread, the atmospheric conditions were such as would be likely to favor the dissemination of particulate matter.

Mr. Power says: "Familiar illustration of that conveyance of particulate matter which I am here including in the term dissemination is seen, summer and winter, in the movements of particles forming mist and fog.

And there are reasons which require us to believe particulate matter to be more easy of suspension in an unchanged form during any remarkable calmness of atmosphere.