The air was cooling down toward evening at Sebastian, where an unpicturesque collection of wooden houses stand upon a branch line on the Canadian prairie. The place is not attractive during the earlier portion of the short northern summer, when for the greater part of every week it lies sweltering in heat, in spite of the strong west winds that drive dust-clouds through its rutted streets. As a rule, during the remaining day or two the temperature sharply falls, thunder crashes between downpours of heavy rain, and the wet plank sidewalks provide a badly-needed refuge from the cement-like "gumbo" mire.