SUGGESTIONS TO COLLABORATORS. 



The present writer hopes to receive contributions from travelers and 

 observers, not only in North America, bnt in other parts of the world. 

 Such collaboration will always receive due credit, and when practicable 

 will be reproduced in the language of the collaborator. 



The number and the importance of the contributions received upon 

 the collateral branch of sign-language encourages the hope of similar 

 success in this application for assistance in the monograph on picto- 

 graphs now in preparation. 



The main object of the classification both of the text and of the 

 illustrations in the present paper has been to stimulate the research 

 and assist the collaboration invited, so that reference to the various 

 preceding headings is unnecessary. Some practical suggestions may 

 however, be offered as follows : 



As a small drawing of large rock inscriptions may give au exagger- 

 ated 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 suffi- 

 ciently close and accurate to show the character of the work. It is de- 

 sirable 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 

 peeking; 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 weather- 

 ing or erosion, together with the exposure, or any other feature bearing 

 on the question of antiquity, would prove important. If actual colors 

 arc 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 ihe 

 points most needed for interpretation. Sketches, or still better, photo- 

 graphs 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 



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