As a small drawing of large rock inscriptions may give an exaggerated idea of the degree of finish or fineness of the subject, it is desirable, in every instance, to affix the scale of the drawing, or to give a principal dimension that may serve as a guide. A convenient scale for ordinary petroglyphs is one-sixteenth of full size. The drawing should be sufficiently close and accurate to show the character of the work. It is desirable to note the lithologic character of the rock or bowlder used; whether the drawing has been etched into the face of the rock, or pecked in more deeply with a sharp implement, and the depth of such pecking; whether the design is merely outlined, or the whole body of the figures pecked out, and whether paint has been applied to the pecked surface, or the design executed with paint only. The composition of paint should be ascertained when possible. The amount of weathering or erosion, together with the exposure, or any other feature bearing on the question of antiquity, would prove important. If actual colors are not accessible for representation the ordinary heraldic scheme of colors can be used. That sketches even by fair artists, are of not high value in accuracy, is shown by the discrepant copies of some of the most carefully-studied pictographs, which discrepancies sometimes leave in uncertainty the points most needed for interpretation. Sketches, or still better, photographs are desirable to present a connected and general view of the characters and the surface upon which they are found. For accuracy of details “squeezes” should be obtained when practicable. A simple method of obtaining squeezes of petroglyphs, when the lines are sufficiently deep to receive an impression, is to take ordinary manilla paper of loose texture, and to spread the sheet, after being thoroughly wetted, over the surface desired, commencing at the top. The top edge may be temporarily secured by a small streak of starch or flour paste. The paper is then pressed upon the surface of the rock by means of a soft bristle brush, so that its texture is gently forced into every depression. Torn portions of the paper may be supplied by applying small patches of wet paper until every opening is thoroughly covered. A coating of ordinary paste, as above mentioned, is now applied to the entire surface, and a new sheet of paper, similarly softened by water, is laid over this and pressed down with the brush. This process is continued until three or four thicknesses of paper have been used. Upon drying, the entire mold will usually fall off by contraction. The edge at the top, if previously pasted to the rock, should be cut. The entire sheet can then be rolled up, or if inconveniently large can be cut in sections and properly marked for future purposes. This process yields the negative. To obtain the _positive_ the inner coating of the negative may be oiled, and the former process renewed upon the cast.