Another class of symbols was worked out in wampum. The popular idea of wampum seems to be that it was a kind of Amerind money, but the money function was only one of its uses. There was another, a mnemonic use, of more importance—that is, it was a means of recording and of communicating mnemonically among the tribes of the North-east. The Iroquois used it chiefly in the form of belts. The beads were generally white, and were used in strings as well as belts, other colours being mingled with the white, as purple and white, or black and white. These strings had important functions in summoning officers, in representing persons, and in conferring authority. But all wampum had a meaning only to those who remembered the particular association of particular forms of it, and the knowledge once entirely forgotten could never be regained. Consequently the ideas with which the belts, etc., were associated had to be regularly brought to mind. Once a year, therefore, they were exhibited in public, and the story connected with each carefully rehearsed so that it should not be lost through forgetfulness. This custom is still kept up among the remnants of the wampum-using tribes. In other tribes, formulæ and drawings were often preserved by certain orders who rehearsed them in the privacy of the kiva. The wampum beads were generally ⅛ inch by ¼ inch diameter—that is, flat discs of shell. They were sometimes also ¼ to ½ inch thick, with the same diameter. When the white men discovered the valuation the Amerinds placed on these beads an attempt was made to introduce some of European manufacture, but it met with only partial success.[53] The average width of a belt is three inches and the length three feet. [Illustration: ORCA OR KILLER-WHALE DECORATION, HAIDA] By some tribes the human body was also used as a surface for the display of pictographs. Among all primitive people the body has been often decorated to a greater or less extent by means of pigments or by tattooing, and even to-day the practice lingers among civilised races, in their sailors and soldiers especially. The primitive totem or tattoo marks are frequently highly elaborate, but the work is not all accomplished at one time. Years sometimes pass before the drawings are complete. The Haidas of the North-west coast are specially given to this form of decoration, and their bodies bear carefully prepared symbols. They are heraldic signs, or the family totem, of the clan to which the person belongs. [Illustration: HAIDA TATTOOING]