(4) The sinew-corded bow area.—Where the bow has a backing made up of a long string or braid of sinew, passing to and fro along the back. This has been carefully studied and described by Murdoch.[15]
He divides the bows into classes, and shows how each of these classes originated, partly by the resources and exigencies of the environment and partly through outside influences. There are practi-cally four classes of this corded or laced pattern, to wit:
(a) The Cumberland Gulf type.—In these the sinew cord, or yarn, is made fast to one nock, and passed backward and forward along the back of the compound bow forty or fifty times. In addition to this, additional strength is given by half turns and short excursions to and fro on the back of the grip. Mr. Murdoch considers this the primitive type of the sinew-backed bow. (Plates LXIV, LXV.)
(b) The South Alaskan type.—The bow is of wood, broad, flat, and straight, but narrowed and thickened at the grip. The back is flat, and the belly often keeled, and frequently a stiffener of wood or ivory occurs under the sinew lining. There is a subtype of this bow from the Kuskoquim area, in which the ends bend backward abruptly, so as to lie along the string, as in the Tatar bow. In this type the strands of sinew cord lie parallel, pass entirely from end to end, and the last one is wrapped spirally around the rest. The whole of the broad part of the limbs is often seized down with spaced spiral turns of the cord. Next to the Cumberland type this is simplest, and is only a slight departure from it. (Plates LXV-LXVI-LXVII.)
(c) The Arctic type.—The bow is shorter and narrower, the ends are often bent as in the Tatar bow, and strips of sealskin are put under the backing. The cord is always braided sinew, passes from nock to nock, but is laid on in a much more Complicated manner, and much more "incorporated with the bow." The whole process of laying on the backing is minutely described by Mr. Murdoch. (Plates LXVIII-LXIX-LXX.)
(d) The Western type.—Bow broader and flatter than the last, but less contracted at the grip, either straight or Tatar shape. The backing is in three parts, none of which extend as far as the nocks. The first cable goes from end to end near the nocks; the second from elbow to elbow, say afoot from each nock; the third along the straight part of the back. The cables become practically one along the grip. The method of laying down and knotting this intricate lashing must be studied from the figures (Plates LXXI, LXXII,) So that in the Eskimo area we have: (1) The plain or self-bow, of one piece; (2) the compound bow, of whalebone, antler, bone, ivory or wood; (3) the compound and sinew-corded bow, (4) the single-cabled straight bow; (5) the single-cabled Tatar or three-curved bow; (6) the complex-cabled straight bow; (7) the complex-cabled Tatar bow; (8) the three-cabled straight bow; (9) the three-cabled Tatar bow.

The material of bows varies geographically. Beginning in the south the regions may be roughly marked off—
(1) Mexican border: Cottonwood, willow, mezquit, bois d'arc, juniper.
(2) Southern United States: Hickory, oak, ash, hornbeam, walnut.
(3) Northeastern United States: Hickory, oak, ash, walnut, hornbeam, sycamore, dogwood, and, indeed, any of the many species of hard wood.
(4) Mississippi Valley: Same as on the Atlantic slope.
(5) Plains: Bois d'arc coffee tree and ash, wood procured in commerce.
(6) Interior basin: Mezquit in the south, abundant woods in the north, hard and elastic; species not determined.
(7) California and Oregon: Evergreen woods, yew, spruce.
(8) Columbia River: Same as California.
(9) Southeastern Alaska: Willow, spruce.
(9) Western Canada: Birch, willow, maple, spruce, cedar.
(10) Eskimo: Driftwood and timber from whale ships and wrecks.

The bow-string among the North American tribes was made of the following:
(1) Strips of tough rawhide plain or twisted.
(2) String made of the best fibers of the country-hemp, agave, etc.
(3) The intestines of animals cut into strips and twisted.
(4) But most frequently of sinew.

The strip of gristle extending from the head along the back and serving to support the former, and those taken from the lower part of the legs of deer and other ruminants were selected. These were hung up to dry. For making bow-strings the gristle was shredded with the fingers in fibers as fine as silk in some tribes, but coarser in others. These fibers were twisted into yarn on the thigh by means of the palm of the hand, after the manner of the cobbler. For making the twine some tribes employed only the fingers. Taking two yarns by one end between the tips of the thumb and forefinger extended of the left hand, the twister seized one yarn with his right hand, gave it two or three twists and laid it down on the palm of the left where it was kept in place by the fingers. Seizing the other yarn he repeated the process, brought it over the first yarn, laid it on the palm, caught the other yarn with the fingers of the left and seized the yarn first twisted with his right hand, all without losing a half turn. The writer has seen this work done with great rapidity. New strands of shredded sinew or vegetable fiber may be introduced at any time.