The mowing machine’s whirring sounded cheerfully from the old buffalo wallow south of the claim shanty, where bluestem grass stood thick and tall and Pa was cutting it for hay. The sky was high and quivering with heat over the shimmering prairie. Half-way down to sunset, the sun blazed as hotly as at noon. The wind was scorching hot. But Pa had hours of mowing yet to do before he could stop f…