[Illustration: Fig. 20 (50-4380). Whirlwind Design, from the Handle of a Club. Length, 5 cm. Fig. 21 (50-4244). Whirlwind Design, from a Popgun. Length of design, 7.5 cm. ] ----- [17] Wissler (The Journal of the American Folk-Lore Society, October-December, 1905). THE THUNDER. The thunder is a very important deity among all the Indians of the Plains, and is usually associated with military exploits. While the Dakota generally regard the thunder as a bird, usually symbolized by the eagle, yet they sometimes speak of it as a horse, a man, or a dog. The horse always appealed to them as a creature of mysterious origin, and in many cases was assumed to have been given by the thunder. In any event there is an association in their minds between the power of a war-horse and the thunder. The thunder is often represented by a zigzag or wavy line, usually in red; but this symbol really represents the power of the phenomenon in the abstract, because the Indian does have the conception of a force in nature. Consequently this graphic symbol is also a general sign for the presence of mysterious supernatural power. The whistles made from the leg and wing bones of eagles, and used among the Plains tribes, are generally employed by the Dakota to symbolize the cry of the eagle as a representative of the thunder-bird. In battle, or sometimes in stress of great trial, they are sounded to call up the power of the thunder to rescue the unfortunate one. As a rule, a zigzag line is scratched down the sides of these whistles. In this connection it is interesting to note the following:— “Before daylight I set off with five Indians. . . . This caused a halt, as we were surrounded and began to suspect that the enemy had planned to cut us off. The Indians put on their war-caps, uttering some few words which I could not hear distinctly, and then began to whistle with a small bone instrument which they hung around their necks for that purpose.”[18] This account (1807) by an acute observer is interesting, because our present knowledge enables us to understand the muttered prayers and the use of the whistle. [Illustration: Fig. 22 (50-3023). Whistle, of Bone. Length, 19 cm. ]