In this manner the ancient Peruvians kept the accounts of their army. On one string were numbered the soldiers armed with slings; on another, the spearmen; on a third, those who carried clubs, &c. In the same manner the military reports were prepared. In every town some expert men were appointed to tie the knots of the quipu, and to explain them. These men were called _quipucamayocuna_ (literally, officers of the knots). Imperfect as was this method, yet in the flourishing period of the Inca government the appointed officers had acquired great dexterity in unriddling the meaning of the knots. It, however, seldom happened that they had to read a quipu without some verbal commentary. Something was always required to be added if the quipu came from a distant province, to explain whether it related to the numbering of the population, to tributes, or to war, &c. Through long-continued practice, the officers who had charge of the quipus became so perfect in their duties that they could with facility communicate the laws and ordinances, and all the most important events of the kingdom, by their knots. All attempts made in modern times to decipher Peruvian quipus have proved unsatisfactory in their results. The principal obstacle to deciphering those found in graves consists in the want of the oral communication requisite for pointing out the subjects to which they refer. Such communication was necessary, even in former times, to the most learned quipucamayocuna. Most of the quipus here alluded to seems to be accounts of the population of particular towns or provinces, tax-lists, and information relating to the property of the deceased. Some Indians in the southern provinces of Peru are understood to possess a perfect knowledge of some of the ancient quipus, from information transmitted to them from their ancestors. But they keep that knowledge profoundly secret, particularly from the whites. That the general idea or invention for mnemonic purposes appearing in the quipus, was used pictorially is indicated in the illustrations given by Dr. S. Habel in The Sculptures of Santa Lucia Cosumalwhuapa in Guatemala, etc., Smithsonian Contributions to Knowledge, [No. 269], 1878, Vol. XXII, page 85. Upon these he remarks: