Dr. Whitman perceived that he was standing on the edge of a powder magazine, and, during the summer of 1847, he arranged to acquire the mission property of the Methodists at The Dalles, a hundred and sixty miles down the River, intending to remove thither in the spring. But meanwhile, the explosives being all ready, the spark was prepared for igniting them. During the summer of 1847 measles became epidemic among the Indians. Their method of treating any disease of which fever was a part was to enter a pit into which hot rocks had been thrown, then casting water on the rocks, to create a dense vapour, in which, stripped of clothing, they would remain until thoroughly steamed. Thence issuing, stark naked and dripping with perspiration, they would plunge into an icy cold stream. Death was the almost inevitable result in case of measles. Whitman, who was, it should be remembered, a physician, not a clergyman, was skilful and devoted in his attentions, yet many died. Now just at that time a renegade half-breed known as Jo Lewis seems to have become possessed with the diabolical mania of massacre. He made the Indians think that Whitman was poisoning them. Istickus or Sticcus, a Umatilla Indian and a warm friend of Whitman, had formed some impression of the plot and suggested the danger. Whitman's intrepid spirit laughed at this, but Mrs. Whitman, though equally intrepid, seems to have felt some premonition of the swift coming doom, for the mission children found her in tears for the first time since the death of her beloved little girl eight years before. The Doctor tried to soothe her by declaring that he would arrange to go down the River at once. But on that very day, November 28, 1847, the picturesque little hill rising a hundred feet above the mission ground, now surmounted by the granite shaft of the Whitman monument, was observed to be black with Indians. It was evident from various sinister aspects that something was impending.