WITHu the most popular heat motifs that illustrate summer every year include happy people bathing in fountains, eating ice cream in the shade of a tree, populating cafes and jumping into lakes. The images that have reached us from Canada and the United States in the past few days tell nothing of this summer ease. They are documents of desolation and despair. Lytton, a town about 250 kilometers northeast of Vancouver, where the temperature rose to a record 49.6 degrees last week, consists almost entirely of rubble and ash after a devastating fire. The fire roller needed less than twenty minutes for its work.