The maul was merely some form of wooden club; the most common type was made by cutting away part of the length of a small balk to form a handle, the remainder being left to form the head. The swelling of the trunk of a small tree at the ground, where the roots form, was also utilized to give weight and bulk to the head of a maul. It could be hardened by scorching the head in a fire. Another method of pounding and driving was to employ a stone held in one hand or both. Stone hammers were rarely employed, since the maul or a stone held in the hand would serve the purpose. The birch tree that was to supply the bark was usually selected far in advance of the time of construction. By exploring the birch groves, the builder located a number of trees from which a suitable quantity of bark of the desired quality could be obtained. Samples of the bark of each tree were stripped from the trunk and carefully inspected and tested. If they separated into layers when bent back and forth, the bark was poor. If the "eyes" inside the bark were lumpy, the bark in their vicinity would split too easily; this was also true if they were too close together, but if the eyes on the inside of the bark appeared hollow there was no objection. Bark that was dead white, or the outer surface of which was marked by small strips partly peeled away from the layer below, would be rejected as poor in quality. Preferably, bark was stripped from the selected trees during a prolonged thaw in winter, particularly one accompanied by rain, or as soon as the sap in the trees had begun to flow in early spring. If this was not possible, "winter" bark, as described on page 14, was used as long as it was obtainable. Only dire necessity forced the Indian to use bark of a poor quality. Fall peeling, after the first frosts, was also practiced in some areas. The work on the tree was done from stages made of small trees whose branches could be used in climbing, or from rough ladders constructed of short rungs lashed to two poles. When steel axes and hatchets were available the tree could be felled, provided care was taken to have it fall on poles laid on the ground to prevent damage to the bark in the fall and to keep the trunk high enough to allow it to be peeled. Felling permitted use of hot water to heat the bark, and thus made peeling possible in colder weather than would permit stripping a standing tree. Felling by burning, however, sometimes resulted in an uncontrolled fall in which the bark could be damaged.